So after the trade, you'll no longer have a top closer, and Kelly Johnson will still be your 2nd baseman. Stand pat. There is no time table for Utley, and he has made comments along the line of having to look out for his career, not just this season.
Kelly Johnson is not the answer at 2B. If you are loaded with closers, you should do the trade. Otherwise, you might want to wait and see on the recovery of Utley
I agree with everyone else. No way, you could get better value than Utley. If you really wanted Utley you should be able to get him when he is a lot closer to coming back and get saves in the meantime.
If this is a roto/weekly categories league and you are fine on saves, target a weakness. If you are in a points league target a weak position but you would likely have to package Feliz with someone else.