I don't think the petty squabbles of the Successor States will matter much when the ilClan invades and conquers them.
Look, I can't 100% predict what's going to happen when IlClan comes out. But we know certain things occur, and we've watched the story unfold to this point. Sure, Stone could reveal that he's been the Master all along, and unveil a thousand regiments of superheavy 'Mechs and a hundred battleships, all equipped with nuclear and biological weapons, burn the Inner Sphere, and then claim ilClanship because he's actually a Wolverine. Or, for a less-extreme example, Stone could blast every Clan invader out of Terran space with WMDs from upgraded Blakist weapons platforms...except we know that doesn't happen. Some Clan or another figures out a way to conquer - or at least merge with - The Republic, and they go on to conquer - by treaty or force of arms - the rest of the Inner Sphere. We've seen 90% of the story so far, we know who the heroes and villains are, and we can make some predictions based on their past actions and motivations.
We know that Stone did not push for advanced weapons projects. Sure, the Fortress is some kind of Blakist hyper-tech, but it is defensive in nature. The Republic didn't start working on advanced offensive technology until after the Blackout, through the RISC project. I peg the odds of Stone reactivating Dragon's Breath - which, again, was responsible for destroying a significant portion of North America's Atlantic coastline - at a hard zero.
Furthermore, what kind of a damp squib climax would that be? After almost twenty real-world years of plot build-up, it all ends with a Clan fleet going "poof" in space? Thousands of man-hours of work, dozens of books and games, over half the time BattleTech has existed, all coming down to a dozen rolls to-hit. That would be beyond insulting.