I agree the fact that he wants to be done with free agency increases the chances of him leaving OKC. Its just not clear where he will go. If these reports are right though, it suggests that he has done some serious thinking about leaving OKC, supporting the view that he knows that Westbrook is a goner. His top choices have to be Golden State, San Antonio and Boston.
Looking at each, San Antonio offers him Pop and two other stars in Leonard and Aldridge - he will also be viewed as the Spurs primary scorer. That said, they would have to jettison some players to make this work and he and Aldridge aren't the perfect pairing though Popvich could definitely make it work. The negatives here are the Spurs will have to be creative to build a bench rotation (they are good at this of course) that they still have to go through the meat-grinder of the West. I would add one more thing - Pop is 67 and has been at this a long time. How much longer does he coach? If I am Durant, that is a concern.
The Warriors offer Kerr, and their big three and while the reports say the market doesn't matter, he gets to live in the Bay Area where he will have both business (venture capital) and sponsorship opportunities. The downside of the Warriors is that he won't be their primary scorer and that touches will be fewer than he has seen in his entire career. The other negatives that apply to the Spurs apply here - the Warriors will have to lose some positional depth to sign Durant (Bogut, Ezeli and Barnes would all be goners), though the Warriors would make that trade-off easily. But the Warriors with Durant still have to get through the West.
Boston offers Durant the opportunity to be the clear leader, even with another max free agent. They have tradition, a strong organization and Stevens at the helm, which should be attractive. They also have organizational depth and their plethora of picks ensure that more help is on the way. Finally, they play in the East where the only roadblock is coming out of Cleveland. On the flip side, there are no max free agents out there who are clear lay-up pairings with Durant and the rest of the C's roster is essentially made up of good rotation players. That said, the Celtics have the assets to add more quality players as opposed to shedding them to get Durant. And Boston, while a cold weather city, offers similar business and sponsorship opportunities to Golden State.
Since we are just having fun here, if Durant is going to leave OKC, I think it comes down to either Golden State or Boston. GS has a lot of talent, a strong organization, a great coach and an attractive market. Boston has less talent but a good organization, a great coach and a decent market. They also offer Durant more of an opportunity to be "the guy" and build his legacy than just about any other choice. It really will come down to how he wants to try to win a ring - as part of a collective or by being the clear leader.