There would have to be a fundamental break down in either

a) the consensus mechanisms
b) the protocol itself

Which could not be resolved

It is unlikely it would just become worthless given the market advantage it has, the tried and tested security system it possesses based in cryptography - math is the language of truth after all.

The decentralised ledger it allows the world to share

The ability to send value across borders in a permissionless way

These things amongst others give it value