If we do part ways with Ten Hag - and I'm still hoping, probably in vain, that he can turn things around - then pivoting to a Simeone or similar would be a disaster. I'd want somebody with similar ideals who would be keen on a similar profile of player, rather than yet another complete 180 that throws us into yet another years-long transitional period.
Luis Enrique was who I wanted before Ten Hag, but he's obviously off the market now. Maybe Arne Slot? Although I could see a lot of fans going, "Yuck, Dutch again," or something.
Alonso is a complete non-starter, Zidane I think would be an instant flop even if he did want to come, and aside from that, I don't see much out there.
I think the structure of the club is fecked like everyone else has said. Maybe wishful thinking but I'd like to see what Carrick could do. One of the most tactically astute players I've seen playing the game so you'd hope that might translate. He is obviously short on experience though at this level.
Even if he wasn't having a pretty torrid time at Middlesbrough, I don't think he'd be an option. After having front row seats to the evisceration of Ole, I doubt he'd have any intention of taking the job. You could also argue that we kind of know what he'd do here, given he was such a big part of that setup.