Is the following scenario possible?
- Kramnik reaches the final of the World Cup, so Karjakin qualifies on ranking
- Karjakin does very well at the last Grand Prix tournament and finishes third in the end ranking
- Carlsen beats Anand to become world champion and Anand retires from chess
- Anand is replaced by Karjakin (3rd place at Grand Prix)
- Radjabov qualifies anyway based on ranking!

Sadly, no, not as I understand it.

"Replacements - If any replacement is needed due to withdrawal or refusal of participation, the first reserve player from the final standings of the FIDE Grand-Prix 2012/2013 will be invited. Any futher[sic] replacement needed will be fulfilled from the average rating list described in article 2.4 above."

So in your scenario Karjakin would not be both a qualifier by rating and the first alternate. The first alternate would be whoever finished fourth in the Grand Prix, since they specify "first reserve player from the final standings" rather than explicitly saying "third place".

Now they DO turn to the ratings list if they need a second alternate. So if Kramnik gets to the World Cup finals and Karjakin thus qualifies by rating, and then for whatever reasons TWO of the eight players to qualify end up unable to play, then Radjabov could get in on ratings as the second alternate.

thanks, another question:
what happens in the not so likely scenario that Caruana beats Vachier-Lagrave and Kramnik to get to the World Cup final, and also double qualifies by winning the last Grand Prix tournament? would Mamedyarov qualify for the candidates based on his third place in the Grand Prix, or would it be Karjakin based on ratings?

OK, I found the answer myself, in my above scenario it would be Mamedyarov who would qualify

Correct, it would be Mamedyarov. Plus the first alternate would be whoever finished fourth in the Grand Prix standings, with Karjakin as only the second alternate via ratings.

And suddenly five of the eight spots in the field are locked in! Congratulations to Andreikin, the surprise qualifier out of the World Cup!

Next up is the final leg of the Grand Prix, from September 18th to October 2nd, which will finalize a sixth spot (and lock in who our first alternate is).

Then comes the World Championship match in November, and the field will be all set except for the wild card. I have no idea when they plan to announce that, but once we know the exact list of options we can have a lot of fun speculating

Nice work creating and updating this summary, BJJ.

just saying that seven (not eight) of the participants in the Paris Grand Prix can finish third in the final ranking (because Karjakin doesn't participate any more)
Caruana seems to have real chances of winning the tournament after today, nothing certain at all, but he has a chance

Both good true points (given that "today" when you posted it is now yesterday), but Caruana's chances of an outright win took a big hit with his loss to Nakamura today.

Caruana beat Gelfand today, and looked like he'd be tied for the lead with three rounds to play (as Nakamura was worse for most of his game). It seemed he was giving himself a good opportunity for that outright win to get into the Candidates.

Then Nakamura equalized the position... and then in a drawn position he flagged Chucky and now HE'S in clear first, half a point ahead of Caruana and Gelfand. Half a point back with three rounds to play and needing a clear (untied) first, I have to think Caruana's odds of earning the Candidates berth are pretty low at this point.

On the other hand, if Naka can hold onto HIS lead and win clear first he can put himself in that key third place position, and hold down the "first alternate" spot. Also I think the win should have given him a personal record new highest live rating.

This Grand Prix thing is the most confusing event structure imaginable and I just absolutely hate it.

I'm just glad BJJ is here to explain all of this to us. I'd have NO CLUE if he didn't do these fantastic updates.

Keep up the great work, BJJ.

With the last leg of the Grand Prix wrapping up, the field is all set in stone, except for the wild card (and the question of who loses the World Championship match).

So . . . if they pick Caruana for the wildcard (seems a coinflip with Nakamura) then is Radjabov the next in line? If so, it would make a case for choosing Nakamura for the wildcard - that way, if there's a vacancy (say Anand retires) they get current numbers 4 and 5 instead of 4/5 and 28.

I think if Caruana becomes the wild card (but he needs a sponsor for that, don't think that will be easy in Italy) then Gelfand becomes the first alternate (4th place in Grand Prix)

Confirmed.

Technically the entire field of eight is chosen prior to determining alternates, and the first alternate is the highest finisher in the Grand Prix who did not make the initial field of eight. I've been saying #3 for simplicity's sake, because of course if the Grand Prix #3 finisher (Caruana) is not in the field, as currently projected, then it's him. If he gets the wild card spot, though, then Grand Prix #4 is first alternate, which as tony37 said, is Gelfand.

The second alternate is the highest rated player (on those average rating lists) who did not make the initial field of eight. This will be Radjabov, unless somehow Radjabov is awarded the wild card (lol).

Caruna would have qualified if he won today. Instead he choose for three fold repitition less than 20 moves into the opening for a draw.

Speechless

but if he would have lost (which was more likely than him winning if you ask me, those connected passed pawns are no joke) then Gelfand would have been the first alternate
maybe he trusts Anand to retire from chess after he loses his title

I'm not going to constantly update the live rankings in the OP every time they shift, when there's multiple tournaments going on simultaneously with a total of (five or six) people from the projected Candidates field in it (depending on whether Caruana is ranked ahead of or behind Nakamura at any given moment). So the OP does not currently reflect that at this moment Caruana is now ranked #3, Kramnik #4, and Nakamura #5, making Caruana the projected wild card. This is after Caruana won in round 1 of the King's Tournament today while Kramnik lost to Andreikin in round 3 of the Russian Superfinal. I'll see where things fall when those tournaments (the Russian Superfinal also has Karjakin in the field), and Bilbao Masters (with Aronian and Mamedyarov participating) all conclude, and then do another update.

the tournament will likely be in Khanty-Mansiysk in Russia, so Grischuk is the most likely wild card, which would be 4 Russians in the tournament (incidents involving Topalov are to be expected)
http://www.chessdom.com/bulgarias-ca...-likely-venue/

I had not looked into the bidding process yet, and wasn't aware that bids were already submitted. If those are the only two bids then yes, Grischuk is now a pretty big favorite for the wild card spot. Great info!

following the Russian superfinal I saw on their site that the candidates tournament will indeed be in Khanty-Mansiysk, due to withdrawal of the Bulgarians
in Russian: http://russiachess.org/news/all/turn...idet_v_khanti/
on twitter: https://twitter.com/bbalgabaev
I expect there will be an article on chessdom.com but I don't see it yet

Yeah, that definitely makes Grischuk the favorite for the wildcard spot (although Svidler is also a plausible option, and more so if he is the Russian Champion after these tiebreaks he's currently playing against Nepo). I'm still waiting to update the OP until the Russian Superfinal and King's are both over, so that everything's clean and not changing again day to day. Grishchuk will be the projected wildcard at the next update, though.

Who selects the wildcard, the tournament hosts? While Grishuk and Svidler are obviously exceptional players, if Caruana wins today (currently +.8 vs. Wang Hao in the Kings tournament), he'll be over 2800 and world #2; it'd seem a shame to pass him by.