There are two premises to this argument:
1) It's been widely reported that Durant is not a lock to sign a 1 + 1 this summer and could possibly sign a long-term deal. That is,
he's not going to go through this free agency period two summers in a row, because he
values stability and
doesn't want to be in the spotlight all that much. This is very much in line with his character. So we should expect that the team he chooses this summer will be the team he chooses long-term, and unless there's a catastrophic meltdown, he won't be looking to change teams again next summer. And this doesn't necessarily mean he won't still sign a 1 + 1. He probably still will just for financial reasons and for flexibility in case things don't work out too well. Source:
http://www.cbssports.com/nba/news/report-kevin-durant-wont-necessarily-sign-short-term-deal-in-free-agency/.
2) It's
HIGHLY suspected around the league that Russell Westbrook will
leave the OKC Thunder next year in free agency. The suspected target is Los Angeles, because he's both from there and played his college ball there. To me, this is already a foregone conclusion. Westbrook is a large market/high visibility kind of guy who loves fashion and the big lights, which is pretty much the opposite of KD, and that kind of stuff might mean just as much to him as playing in his hometown and in a big market like LA. And you can't really blame him, either. OKC is not a large market that he would thrive in, and most people want to be back closer to home.
Thus, you can bet your arse that KD and Westbrook have had very frank conversations about next summer. It's no coincidence that the noise about him leaving and him looking for a long-term option has grown in the last several weeks when previously it was being reported that he was almost a lock to stay in OKC.
I think he knows that Russell is LA-bound next summer, so he's looking to make his permanent move this year rather than do this two years in a row. He has good team options, so it's not like he's really hurting himself here.
Therefore, if you accept that:
A) he doesn't plan on going through this free agency process two summers in a row (which is in line with his character and a fairly safe bet); and
B) Westbrook is most likely gone in 2017 (which is also widely speculated and a fairly safe bet); then
C) it's more likely that Durant leaves OKC for another team than stays there for the long-term.
Who that team is is another story in itself, but I would bet that KD changes teams this summer.