If Chelsea arent prepared to sell him, and he came here, played and done well then he would have a decision to make on where his future lies.
Chelsea take him back and either start using him or deflate him even further by not playing him after he got used to game time for us.
Whether Arsenal, Spurs or Leicester would take him should make no difference to us. For a relatively low sum on a transfer, or we pay a small loan fee and cover his tiny wages on a loan, if he improves our team/squad then brilliant.
Im sure you wouldnt have turned your nose up at Foden on loan last summer.