[21]

Bitcoin can transition to a quantum resistant system before quantum computers are a reality. At the moment there is no clear post-quantum algo winner, but when the industry settles on one, bitcoin (and the whole world - SSL, ...) will switch. It's not the secp256k1 elliptic curve which defines bitcoin, it's just an implementation detail.

I'm pretty sure most cryptography experts would consider nuclear war more likely than a breakthrough in crypto which breaks bitcoin (and the rest of the world). Yes, it's possible, but I wouldn't lose sleep over it.

Gold supply is elastic, unlike bitcoin which is hard coded.

Gold mining is dictated by the gold price. When gold price goes up, miners start to dig again in regions that were too expensive before. When price goes down, they stop. With a suitable (huge) gold price, it makes sense to just filter it out from ocean water. And let's not even think about giant gold asteroids which are out there.