If there is no hard fork and segwit2x is adopted smoothly, it will help bitcoin immensely, especially as most transactions still happen without using segwit, so that 2mg is needed.
If there is a hard fork, yes, it will weaken bitcoin quite a bit.
It's a hard fork. That's how it was designed from minute one. It can't be adopted smoothly unless every single node abandons Core and follows this. That's impossible.