Umm anyone who has studied distributed systems understands a fully distributed system cannot scale past a certain limited point. That's not controversial. That's just reality.

LN, for example, is adding degrees of centralization to achieve better scaling. Human systems have a tendency towards centralization and consolidation of power/authority as well, as we see in various ways already with Bitcoin (China, Ver, Core).

There's overwhelming evidence to believe that the future of Bitcoin is much more centralized, at which point it starts to resemble the systems we already have but with horrifying disadvantages: your entire transaction history is public to everyone, your identity can be linked to your wallet through exchanges, etc.

One example is that BTC's transactions costs are getting more expensive as time goes on. They were supposed to start going down after the most recent hard fork, but I don't know if has been the case.

Another example is that the electricity cost to run the system is going up at an unsustainable pace. Eventually they'll have to switch to an new way to propagate the blockchain something other than Proof of Work mining.

Most likely though, these problems will be solved with some kind of hard fork rather than BTC dying.