I'm thinking that if they can't get Ronaldo to come in January they should look at acquiring Reus. Dortmund has been in a free fall since Lewandowski and Götze left. Potentially Hummels and Reus may be available. Reus himself stated if we are playing in the Champions League, next year he will come.
Right now they line up as:
DDG
Rafael-Jones-Rojo-Shaw
Fellaini
Herrera-Blind
Di Maria
Rooney-Falcao
And RVP, Mata, Januzaj, Carrick on the bench.
One player I would want Utd to bring back home would be Paul Pogba but that is a silk to no chance.