Leave him where he is and let him develop, even without injuries there's been a weird obsession with bringing him back. Moyes isn't known for starting youngsters, chances are he comes back and festers on the bench while Moyes does some square pegs and round holes.
The window will probably depend how Senegal do anyway, if they're out earlyish we probably won't sign anyone and even if they make the final they'll be back by about the 20th Jan.
Leave him where he is. If we have Rohl fit then he has to be above Armstrong in the pecking order anyway, so let him end the season with Preston and get games every week under his belt.
When Moyes started Dibling in the cup it was the first time in 180 odd games that he started a teenager, and he's hardly given him a look in since then despite what we spent on him. If we bring Armstrong back he'll bench him and use him as cover, he's not going to start playing him every game.
Also, as we've seen with the shite that's come up over the last few years, that the PL is a different level to the Championship these days. Doing well there doesn't mean he's ready to play every week in the PL.