Phillipou is a solid fighter, but he's nothing special. He'll never get a title shot or be a true contender, and at best he'll be a gatekeeper.
I don't like the idea of him waiting for the outcome of a fight that takes place in 3 months, let's throw him in there with Hector Lombard. Lombard would be his toughest opponent to date, and for Lombard it would arguably be a bit of a step down in competition from Palhares, but not much if any. It could prove Lombard wasn't a fluke and establish how good he truly is, while giving Phillipou a challenge to test himself.
Costa's in the top ten now and is a lot better than Palhares is, I'd go for the match up but I don't think anything will be announced with anyone until Vitor and Bisping fight.