I would say it's even more than that, Bethesda are putting a good spin on this, but Microsoft have basically taken the franchise off Bethesda and given it to obsidian entirely, it's barely a collaboration.

At the rate Bethesda is releasing games now, we could honestly expect fallout 5 in 10-15 years. Microsoft Gaming's new CEO has started pushing a lot of the studios to actually make things.

The studios themselves have become (validly) afraid of actually releasing mainline games, a good example is valve, where a bad Half Life 3 would hit their reputation hard, and isn't worth it for the money they currently make. Bethesda are already being seen as a company that used to make good games, and they feel safer making money off other revenue streams that aren't a mainline release, that's not to mention the venture capitalism hellscape of 5+ year production styles for games needing to make enormous profit to be viable.

Microsoft doesn't care about this, it can't have half its main studios in development purgatory, it needs games.