First off, AI doesn't act on its own. It can only be used by people. So, it's not AI that's the threat should it be used against Bitcoin in the future; it's anti-Bitcoin people. If so, then the opposite could also be true, that AI can be used by pro-Bitcoin people as well.

If AI can improve mining, then, rather than a threat to Bitcoin's decentralization, it could even be used to boost it.

As to narratives, don't fret. Narratives can only do so much. They can't change reality. Whatever stories built around Bitcoin don't change a bit what Bitcoin is. Just don't trust right away; verify. So far, Bitcoin has survived all kinds of narratives.

As to the market, let everybody use whatever tools available to their advantage, AI included. The Bitcoin market is a free market. The Bitcoin market isn't Bitcoin.

AI-designed chains might be a thing in the future, but I don't see why it's a threat. Again, such capability could also be used in favor of Bitcoin.