Would bitcoin be destroyed if a wealthy organization obtained a CPU majority for a sustained period?
One of the questions you linked to has the wrong chosen answer— Bitcoin can also be destroyed by a sufficiently deep pocketed attacker which corners sufficient marketshare of coins to enable causing debilitating volatility. Probably won't require any where near majority share to create volatility. I added my claim at that question.

Yes Bitcoin can also be destroyed if an attacker cornered sufficient Proof-of-Work to disrupt the system. Even if developers release new protocols after the attack, there will be chaos as to which fork to trust and reputation will be shattered.

Might not even require 51%, as the minority share attacker could cause many transactions to be randomly delayed, which is also potentially debilitating to a currency.

As the prior answer points out, one the keys to hardening a P2P currency is to make the Proof-of-Work more difficult to corner. But that alone is not sufficient, as the volatility of the value is another attack vector. I am contemplating solutions to harden against both classes of vulnerabilities.

Bitcoin might even be attackable simply by talking and enumerating the flaws in it. We could see a crash at any time if enough people become concerned. So public opinion is another attack vector.