Interesting.
If I'm Cleveland, I DON'T do it. Embiid is a once-in-a-decade talent and great 5's are just too hard to find. Cavs desperately need a center. Hawes is unrestriced and isn't a top talent anyway. Varejao is old and is always hurt. Would Parker be an upgrade over Thompson? Sure. But Thompson is at least young and serviceable. I don't think Embiid slips past Milwaukee since they need a replacement for their pothead, Sanders. There really isn't another center in the top half of the draft. Cleveland would have to go with someone like Stauskas or McDermott at #10, but they already have Waiters at SG and Anthony Bennett ostensibly replacing Deng at SF.
As Miami shows, you don't need an elite center anymore, just a strong serviceable, defensive minded one, which Varejao is. Varejao has a couple good years left and can fill the gap for Cleveland until they can draft, trade, or sign a replacement. I think their biggest need is replacing their forward spots, as Deng will probably walk and Tristan Thompson is not a starting caliber big yet. They could take Parker or Wiggins at #3 to solve the SF issue and probably Saric at #10 as the PF. Thompson could back-up the 4/5.