The only reason I could see them releasing a premium console is because otherwise they're going to exit the console market altogether and want to try something new as a last resort, just to see if it works, because if it doesn't, they're in a situation where Xbox (as a console) is relevant to even fewer people than before.
The issue with a premium console is getting anyone to release exclusives for it, so the main draw would be its power. They'd end up in a situation where they might have a larger proportion of whales than other platforms, which might attract some 3rd party releases, but overall, I don't think that seems like a very strong strategy. It gets more attractive if it supports Steam as well, but Microsoft gets no cut for Steam games, and to support Steam, it would probably have to be an actual PC, not just something with 'PC hardware', which kind of complicates things. And what kind of a proper gaming PC could they expect to sell at a premium price that's still profitable but also powerful enough to be attractive. To me, this seems like a very hard thing to pull off with Steam and possibly unfeasible without Steam.
Since it seems like Microsoft is still going to release a new console, my guess would be that it's going to be kind of traditional but have some kind of a hook (or several). Having it be a premium console doesn't seem that likely to me though.