Very Valid I do say from both points of the BOS & Minutemen I'd rather them be the last 2 elite forces of the Commonwealth whether they trust each other or not because at least they understand the technical alliance between them while with the RR/Institute they're both direct enemies to the BOS and each other meaning if both are wiped out with only those 2 left with BOS or MM ending then long ad thr settlements are off limits there shouldn't be any issues as Preston says they'll stay out of the Brotherhood's way and Danse states that their intentions are to destroy the Institute Collect Pre War Tech and protect future dangers like nuclear war & repeat of FEV catastrophes. With both sides having that mutual understanding I feel it would be a rocky but stable agreement equal to cold war unless Teagan goes through with disturbing settlements allied to the Minutemen then it'll lead to War
I'd say Raiders are always gonna be a danger though like look at what happened to Paladin Brandis' Recon Squad they were ambushed by Gunners soon as their vertibird reached their destination luckily The Gunners didn't get get to steal it as it was destroyed otherwise they'd cause chaos with one in their possession considering their advanced tactical training even Recon Squad Gladius couldn't just blast their way into several locations due to raiders having the advantage with buildings used as strongholds whether it's the Brotherhood or Minutemen, Diamond City Security with Turrents or Mercenary Convoys when tangling with Raiders if they have the numbers or even sometimes it can simply be planning in advance they have the advantage as we've seen many times Raiders bribe enemies into being turncoats for extra spoils
Lmao soon as I said this literally just got ambushed by Raiders at Cambridge Police Station a couple scribes and squires went down so seems they're getting bold charging right in