I really wracked my brain for that question. I like to argue the other side, but I can't see anything.
There are zero outs in batteries. LG Chem, Chinese factories, Panasonic (who will basically own the gigafactory as well as others around the world and take any profits), own this space, and the tens of billions in capital and research needed to stay at the forefront mean that Tesla is shut out of competing until at least 2022 when they're selling a million cars (in the best scenario bull case). The idea that they'll sell lots of batteries or "powerwalls" is farcical; the "preorders" have quietly faded away after last year's fanfare. Battery/solar/invertor systems are expensive commodity items, which is why practically everyone who sells them, including Musk's SolarCity, is deep in debt or close to bankruptcy without government handouts.
There are zero outs in car production efficiencies. Unlike space travel, which is a tiny (relative to cars) non-commercial pork barrel, cars are an absolutely cutthroat business where world's-best engineers, designers, supply networks operate on large efficiencies of scale using enormous amounts of capital to generate over a trillion a year in finished goods.
The give you an idea of the scale of the car industry, Ford pulls in $140 billion a year in revenue using $220 billion in assets and incredibly complex and long developed global supplier chains, to produce that revenue, out of which it makes $7 billion in profit and has a market cap not even twice Tesla's (and about the same when you include the value of dividends until Tesla starts paying a dividend in the best case at 202X).
So you can see the problem and how little profit there is in the car business. They're too expensive to be toys like phones - incomes don't support that kind of frivolous spending like the do on iPhones. A weeks' wages (or $60/month, subsidized by a carrier) is nothing to pay for bling and cool; a year's wages is very different. If that kind of money existed, people would already be buying BMWs rather than Fords.
So what's left? Let's take a fanciful scenario - Model 3 comes out in 2018 and is a hit - they sell 500,000 that year at $35,000. This brings in $17 billion and even magically a couple of billion in profit (little chance on the profit, but I'm trying to be fanciful). Great. It's 2018 and there lots of electric competitors coming on the scene from the mainstream, in all shapes and size and ranges and combinations, and Tesla have brought in $15 billion of the $170 billion+ they need to produce cars on the scale that Ford does, competing with a global industry capitalized at 100x that figure. Meanwhile, batteries are becoming cheap enough that 200-300 mile ranges - enough for most uses, are common, and a bunch of ultra cheap 50-100 mile battery + small range extender, non-motive engine that gets rid of range and charging anxiety round out the offerings. Meanwhile a worldwide buildout of next gen battery factories is continuing (it's already well underway) which will collectively dwarf the gigafactory.
You can see how they're not going to make meaningful inroads into this world. While you can continue to offer secondaries on a vastly inflated stock and use that shareholder money to lose this much per car once you factor in capex:
people will always buy (similar to how selling quality steaks for $1 will get you a ton of revenue), but there's a limit to how long you can do this, and patience with Musk is already wearing thin.
So what else is there? Getting there first on (true) autonomous driving? I think that has zero chance, but let's say it has some chance.
What are they going to do with this technology? They don't have mass production ability on the level of Ford for 10+ years by their own estimates, let alone the global industry. Even if Tesla wins, others won't be far behind - months, not years, given how much money is in this research and the fact that it'll mostly depend on hardware/software combos which will look a lot like the
nVidia Drive PX plugged into a multi (multi) camera array.
Full self driving itself is only going to commoditize cars even further and probably decrease global car production volume - engine no longer matters, handling no long matters, many personal driving touches no longer matter. Cars become pods to get around, and the level of sharing goes through the roof.
I just don't see any possible outs for Tesla. I see a long expensive struggle that they're near certain to fail. They don't have the capital, they don't own the self driving hardware, they don't have the software. They're already valued at Ford's level when you include NPV of dividends.
I mean, if anyone has a plausible bull case where Tesla produce more profit in say 2023 than Ford does today, I'd love to hear it.