I doubt the story is true. If their is some truth to it, I rather we loan Welbeck to tottenaham and get him game time like what Chelsea has done to lukaku. This is done to give him consistent game time and help him develop as a striker, rather than playing him all over the place like what we have done to Kagawa. Once Van Persie retires, he can come back and fill his boot when he has established himself as a striker.
Welbeck has been a productive member for United and has been consistently used for our big games, while also showing some noteworthy performances against the lesser opposition. As a reason, I can not see why United would sell Welbeck unless he wants more gametime as a striker. My hypothesis is, that watching sturiddge who was considered his lesser two years ago improved significantly because of consistent game time has made Welbeck question his development at United. If United are not willing to develop a young striker like Liverpool done with sturridge, maybe for his career it is better to seek a team like Tottenham, Arsenal or Everton who could do just that to his career. It would be a great move for Welbeck, but like Chelsea with Sturidge, a bad move for United. In particular when Welbeck and Rooney seems to be our only productive strikers under Moyes so far.