I'm definitely on the ColdCall boat, Silva is ducking Machida. I'm sure Machida will agree to defend his belt against anyone, Silva would be no exception.
Silva always seems really shy about fighting Machida. Machida's fought and hurt his own brother, I doubt he'd have an issue at all. And his managers etc never talk about avoiding that fight.
Silva would get outpointed for four rounds, hurt bad in the fifth and the UD would go to Machida. Clinching Machida would be a bad idea IMO, re: Machida's aggressive sumo tosses from that range.