This production bottleneck is a very temporary thing. They had the same problem with the original Roadster, the Model S, and the Model X. All eventually resolved. I see no reason they won't eventually resolve it for the Model 3, as well.
It may (read: will and has) take longer than they wished, but they aren't in anywhere near the danger of going under as they were with, say, the original Roadster, so this is just a matter of time, in my opinion.
The danger comes in the fact that electric cars are ultimately fairly simple to make (although Tesla does a particularly good job at it), and if their competitors just got their act together, Tesla would have a tough time. But in my opinion, as long as they're the only ones with a really good charging network (the others are both much smaller and much slower... and the few stations that aren't slow require an upgraded car), they have a significant head start on their competitors.
Production bottleneck will eventually clear. But having demand exceed supply is really, REALLY good for Tesla's business as it gives them access to interest-free capital (from reservations) and the reservations also show the existence of sufficient demand to justify financing continued expansion. So, Tesla keeps coming out with new products even before the previous bottlenecks have been cleared in order to maintain the state of having demand greatly exceed supply.
And these new products usually share a technology core, i.e. battery modules and electronics, thus allowing them to traverse as far down the learning curve as is possible, which is a multiplicative effect that improves every other product. Using larger batteries than you might think strictly necessary only amplifies this effect while giving them a quality and performance advantage over their competitors.
Tesla will also have an advantage in their charging network of having cheaper electricity with faster charging than anyone else. The Semi product offers 7 cents per kWh, which is lower than residential rates just about anywhere AND is ultra fast-charging. So assuming they can meet that rate, Tesla will have a large advantage in logistics costs even compared to other electric self-driving providers.