It's fine to speculate what could have been, but historically the record for regional "nation building" of this sort has been mixed at best, given the examples of former Czechoslovakia and Yugoslavia.
Yep. But it was a mess either way. On the other hand, if there was some sort of Central Europe superpower building, Poland would probably have abused that. As it did anyway eventually occupying lands of 3 of its neighbors before being taken down by 4th…
In any case, some sort of Intermarium probably was the only thing that could have prevented WWII in one shape or another.
