The Suns went to the WCF with Shawn Marion as their PF, and he has no inside game at all.
The issue isn't slotting people into positions. It's having an interior presence on either end of the court. Right now, no one on the Suns can score inside (except Richardson, sort of) or defend the paint (except Lopez on one of his five good days per month). So either they'll have to inspire some players on the current roster to acquire those skills, or they'll be a Golden State Warriors clone.
I think it's extremely unlikely that we'll see a trade that improves the Suns this season. The only thing resembling a trade chip is Warrick, and he's just not going to bring that much value. Besides, he's probably the closest thing to a PF the Suns have.