They would have to build a new arena as I believe Philips underwent a recent renovation that completely killed whatever chance of feasibly laying down an NHL sheet of ice w/o obstructed seats. Are taxpayers going to want to pay for another stadium? Doubt it. Is the NHL going to expand past 32 teams? Seems unlikely, which would mean relocation is the only way.
I hated seeing the Thrashers leave and do think they deserved a better ownership situation, but overall I think the NHL has moved on from them for the foreseeable future and is more focused on Seattle right now. I think Atlanta would make a great AHL city FWIW, would finally give the Checkers a natural rival.