The biggest threat to signing him (if he does leave) I think would be Barca or Real Madrid. So it mainly depends on if he wants to go to the prem.
Arsenal cant afford him. Spurs can't afford him. City got rid, Pep said he wouldnt want him back and they have quality and depth out wide (and youth). Chelsea is a mess right now, are seemingly reluctant on spending huge amounts, never give youth a chance and a good chance they dont get top 4 for the 2nd year running. Liverpool have their starting front 3 set, shaqiri as depth but have other gaps to fill before looking for big attacking signings.
United is the no brainer option from a financial and footballing perspective if he comes to the premier league. Saying that, I think he'll probably stay another season so feck knows what happens if he doesnt decide to leave this summer. We should go all out to force it through though.