If BTC were to lose the number 1 position, it is highly unlikely that it would be replaced by another PoW coin. PoS is more likely and it actually would make for a more elegant ultimate track and control blockchain based fiat than bitcoin which is already a close approximation to this monster in itself.

Now if BTC were to be abandoned by the miners in favor of BCH then I could see BTC continuing in that form for some time longer. It is a legitimate fork, this is just a weird (considering the amounts involved) and temporary situation.