I dont think this will ever happen, Ferguson always sells players for a reason and he probably didn't think Smith was good enough for a rapidly developing United squad. However i was left very dissapointed by the sale of this player, because the drive, determination and energy Smith put in to his game was phenominal, i thought he should have at least stayed on as a squad player because it was his work rate and ethic that helped push United over the finishing line in the race for the Premier League in 2006/2007.
It's quite suprising really, over the past few seasons i have seen many threads asking for Alan Smith's return, i have never seen it for any other ex-United player. I think it is mainly because United fans never really got to see much of this player at his best, yet because of his work rate and determination, we always wanted to see him make it at United, sadly, it never happend.