I'd imagine they could find a manager with some pedigree to take over the job next, the problem of course is what that guy inherits.
The big concern for the Mackems (the sensible ones that is...............) is the O'Neill legacy. It's absolutely dire. He's paying overrated, old players top dollar.
Inheriting a squad with players like Cuellar (31), O'Shea (31), Titus (31), Brown (32), Bardsley (28), Vaughan (29), Saha (34) and even Sessegnon (28) just shouts out a massive lack of sustainability.
Unless their owner is literally going to throw good money after bad, how do you turn that situation around?
You sell.
Who do you sell? Johnson, Fletcher and potentially Cattermole are their only players worth anything.
Their next appointment is going to have to be an absolute masterstroke and somebody capable of not only getting a team performing but building an entire infrastructure (scouting networks etc etc) to enable them to compete.
I'd be massively concerned if I was a Mackem.
Edit - there's a reason Lambert, AVB and Rodgers were given jobs this summer. All relatively young, all play good football but arguably all appointed with a (very?) long term vision. That's to build what I have outlined above. They've all replaced yesterdays men. Old school football men. Redknapp, Daglish and McCleish.