1. People losses interest in crypto.
This still would not mean the death of bitcoin. If there are 2+ nodes online, it can be considered as a network (a pretty small one obviously).
2. or Some regulatory policy imposed which enables this ti do.
Regulations can't shut down bitcoin. Thats not how it works.
Regulators can force provider to discard packets which have been flagged as BTC packets. But this can't be forced on 'all' routers.
So thats not a way of shutting the BTC network down.
if all nodes looses interest impossible to back to life again
It is still not impossible. If a miner/node goes back online with the latest copy of the blockchain, it would be 'back to life again'.
Like resuming a paused movie.