It seems to me that we (the audience) are still unsure of exactly how the Capellan/Canopian/Andurien relationship is going to pan out. Some of that I think is just the nature of being at this point in the story - I'm surprised that
there were any MAF units at all fighting alongside the CCAF in IKEO given external commentary. But given the current nature of communication in-universe, maybe that's fine; the maneuvering of interstellar powers takes time to filter out to when the space internet is still down.
Remember, this game is BattleTech, not PeaceTech. They need reasons to keep neighboring factions at each other's throats to drive the wars we play out on the tabletop.
Apologies, because it will seem like I'm picking on you, but I'm not - this is just spurred by a thought I had in the Calamity Kell thread. I think this is a good sentiment to remember, but it's too often used as a reason to justify stilted plots or stuff that doesn't make internal sense. In this instance, if the Canopians and Anduriens make a more formal union or not doesn't meaningfully stop it from being
Battletech, any more than the Ghost Bears and FRR or the Snow Ravens and Outworlds combining does. They're both small powers. And heck, the FedCom era didn't turn into an era of peace, and those were arguably two of the greatest powers of the age.
Peace - or least, periodic gaps where the various factions build their strength, be it by absorption or treaty or alliance or whatever - is a requirement to have battles that have any kind of stakes.
Now, it's entirely possible that in this instance the Anduriens will gamble and lose or gamble and win, but I don't think one is going to lead more to the cessation of wars in the setting than anything else. I, personally, think it would be an interesting shakeup (implausible as I think it is) if the Canopians and Anduriens unite because together they're more of a serious threat to the League and Confederation. Plus who doesn't like a new map? I don't think it seems likely; there's no reason that Magistracy citizens are going to line up behind Ari Humphreys any more than Anduriens are going to line up behind an unrelated Centrella.
To an extreme end, why have any factions have any coherence at all? Surely there's more war if the Lyrans remain fragmented, if the Suns' marches all take up arms against each other, if St. Ives is possessed by the spirit of separatism again, if the League falls apart, etc. etc. etc. On the other end of supposed unification, even the vaunted age of the first Star League saw no end of fighting, even if we just look at the great houses and leave aside the horrors of the so-called Reunification War.