As has been said, with an interim manager I'll be surprised if we bring anyone in.
We don't often do much business in January anyway, and while a new manager should make it more likely that we'd bring players in, an interim manager actually makes it less likely.
If we do, it has to be either a CM or RB. But I can't see it happening, or us spending much on any addition if we do - not unless Rangnick staying on as manager is a very real likelihood.
Obviously the interim manager situation hinders the permanent outgoings as well. As does the very high wages. I can see some outgoings - either on free, like Mata, or on loans - the youngsters and maybe some who want to leave. But I can't see us selling any high profile players for a substantial fee - it's a difficult market, and not many clubs usually pay high fees and wages in January.
So I'm not expecting much movement, and certainly little / nothing that will affect the first team squad to any extent.