Feel free to share your guess, but please back it up.
Does surviving or not depend on the amount of demand?
Or does it depend on the quality of the tech behind the project? Those 2 don't necessarily go hand in hand.
It seems to me that BTC and Ethereum thank their growth prospects to their established names, rather than the tech behind it.
Hmm. I only partly agree with you. Of course it is true that Bitcoin and also Ethereum have the huge advantage that they are just so well known by now. If you talk with people that are not into cryptocurrencies about that topic then for them in most of the cases Bitcoin = crypto and they no no other project of that category. If they know another one, then it is probably Ethereum. So i agree with you here.
I also think though that Ethereum has achieved it's huge market cap because of it's technical abilities and the wide arrange of functionality that it offers. If Ethereum would not be there we probably would still not have the smart contract functionality that enables pretty much every big crypto trend of the last few years. Of course there are other projects now that have the same functionality but they are all copying Ethereum in my opinion.