I can't see this happening, but I'd be all in.
Far rather give him a chance than see Ten Hag get another season
Tbh, I think McKenna, who I rate as a very interesting coach, would stand a much better chance at aunited if Ten Hag does get another season. He needs more experience to take on such a disruptive situation we have right now, it would be better for him as 38 yo specialist coach if the setup with DoF/TechDir//HoR/CEO/Ineos was established before he came, and he will have a better ground to come to if the players have had a more normal season behind them.
I think he has verry little chance of succeeding coming at this point, starting from zero with distraught and frustrated players, some at his own age with ten times his experience, many shot on confidence in themselves or in each other. It could become really, really ugly, and for all the people at this point writing they would give him time, or it can’t be worse than this, there will be thousands typing S H A M B L E S and ITOLDYOUSO angrily into their keyboards if we are 10th placed in octobre under McKenna, some of them national media sports journalists. He might stand for that, but this group of players won’t.
This group of players knows and remembers that they have performed well under Ten Hag under normal circumstances, they know this season is an anomaly, they will be able to learn from both these two seasons and deliver something more akin to Ten Hag’s best level, which has been proven several times to be at least very good. That’s if the dressing room haven’t totally caved in on him.
If it has, this is not the situation for McKenna to come into, IMO. Then it would be better with some unexciting but experienced placeholder to put us within reach of CL for a season or two, hopefully one operating by similar principles as Ten Hag has and Ineos et al wants.
This is really not the best summer to be needing a new manager, looking at the options and their situations.