Looking at our competition to acquire him, it should either be from contenders or fringe contenders and playoff teams. No lower team is giving up assets to pay Rudy Gay, just not happening. And the majority of contenders won't/can't give up a major piece to acquire him. This is who I would guess might be interested: Clippers, Rockets, Jazz, and Thunder, maybe Wizards, Pacers, or Blazers. And a couple of these teams are a stretch but I'll explain why.
I ruled out Celtics. I don't think they are looking to waste any assets on Rudy Gay. Raptors and Grizz he has both played for, so I doubt they want him back. Hornets, Bucks, and Pistons are fringe, but they each have their SF spot covered and paid or will pay their guys from Batum, Tobias Harris, and Giannis and Parker respectively. Bulls don't really have the assets unless the Kings love Taj, but then Gay would have to start at PF or something would be unconventional in that lineup if they are willing.
Pacers have George and Young already, but if they want to make a playoff push they could be interested and maybe move George to SG and put Gay at SF. They have Ellis, Teague, Miles, and Stuckey that are likely assets. Kings could be interested in something there but I don't know if either side is interested.
Wizards have a solid record and could possibly use Gay, they have Porter Jr., Oubre Jr., and Burke as possible assets. The question is who they would be willing to give up and if the Kings want it. They might rather hold on to those young players.
Blazers have Crabbe and Turner locked up long term at 16-19 mil already. And Harkless and Aminu at 7-9 mil. So if Kings are interested in something there, maybe a possibility but Blazers clearly have forwards locked down so they may not even be interested. And they would likely have to try to offload Turner which could be difficult if Kings don't want him. Blazers need a big man more than anything.
Rockets, I doubt they want to give up Ariza or Gordon. So the offer would likely be Brewer and Beverley if they were interested. Not sure if they are interested or if they would do that trade.
OKC can really only trade Kanter for Gay moneywise, and I'm not sure they would or if Kings would be interested considering they have Cousins, but that is an option.
Jazz have Hayward and Joe Johnson, but Burks, Mack, Hood, and Lyles as assets they might be possibly willing to give up in a trade. I don't know if Rudy Gay is that guy but they are making a playoff push.
Clippers clearly need a SF. Would a trade offer around Austin Rivers be appealing? Maybe.
I don't think it is stronger than what we can offer. Basically most of these teams can't give great offers, and if they can, I'm not sure they would want to do it or not or how interested they actually are in him. Three team trade possibilities still exist though as we know. I would guess the two most serious teams that want him would be Thunder and Clippers, but maybe a dark horse team will appear.
I think we would have a great shot because I don't know how many of these teams would actually want him, be willing to give up assets, and pay to retain him. We are in a position that we are willing to give up the right assets and even risk a rental.