Modular designs can absolutely get you a machine that can use shor's to break a bitcoin key. This is chip design 101, combined with quantum mechanics 101.
And this is only one of 60 or 70 separate angles in which an unexpected (but totally plausible) breakthrough can change the game. Do you want to go through all 70? we may not even need qubits at all...
You have to be honest with yourself. You have no idea what will or won't happen. You have no crystal ball. Nobody does.
Google, Cloudflare, Signal, many others have all moved to post quantum. Yet somehow the bitcoin community's only prevention work at the moment is to pretend like it can never happen. Classic head in the sand.
The smart thing is to take it very seriously and move as fast as possible to mitigate it.
