I think that if Tesla were to go belly-up because of some sharemarket issue, that it'd be very easy for all the other manufacturers to back off their BEV plans. Not necessarily outright cancel them, but just not push for it and possibly let it fizzle somewhat.
They'd have the excuse that "Well, Tesla failed, and they were more valuable than all of us combined at one point, so... we'll just be more cautious"
One major issue is adoption. While there's a whole lot of people who want BEVs, price is still a major concern, as is infrastructure.
Tesla make it dead simple with their supercharger network - find a charger, plug in, fast charging happens. The find a charger thing is integrated into the car, and often has feedback about what chargers are busy or unavailable.
Unfortunately, outside of Europe and the UK, the BEV charging story is pretty terrible.
Volkswagon, who arguably have the biggest incentive to make this work, have a pretty atrocious charging experience in the US, as demonstrated by Engineering Explained[1] with their latest and greatest model the 'ID.4'
Europe and the UK have put down standards and basically forced some level of interoperation between charging network systems, which reduced friction for EV owners.
The other issue is getting dealers onboard. If you're someone for whom an EV might make a whole lot of sense, there's approximately zero chance you're going to get recommended an EV, even if the dealer has one to sell you (either because the dealership dont' keep units to test-drive, or the manufacturer doesn't sell a BEV). Dealers hate them, because there's little to no after-sales servicing requirement. I've seen many stories about people basically having to argue or beg a dealer to let them buy or even order an EV.
Perhaps Manufacturers could go with direct sales a-la Tesla, but there seems to still be a lot of political power left in the dealer networks, so that isn't necessarily going to be possible any time soon.
What will convince me that EVs are here to stay is when dealerships are pushing BEVs right alongside their ICEs.
[1] https://www.youtube.com/watch?v=EotuxCptcM4