When the Oklahoma City Thunder lost to the Golden State Warriors in Game 7 of the Western Conference Finals, it felt like a collective gut-check for Thunder fans. 

But this has to feel much worse.

Kevin Durant announced on the Players’ Tribune Monday morning that he will leave the only franchise he’s ever played for to sign a two-year, $54.3 million deal with the Warriors, who lost in the NBA Finals to the Cleveland Cavaliers. Durant will have a player option in the second year, according to ESPN’s Marc Stein. 

“This has been by far the most challenging few weeks in my professional life,” Durant wrote at the Players’ Tribune. “I understood cognitively that I was facing a crossroads in my evolution as a player and as a man, and that it came with exceptionally difficult choices. What I didn’t truly understand, however, was the range of emotions I would feel during this process.”

Durant will join a core that includes NBA MVP Stephen Curry, Draymond Green, Klay Thompson and, likely, Andre Iguodala. Golden State will have to trade center Andrew Bogut while also letting forward Harrison Barnes and center Festus Ezeli walk in free agency to clear enough cap room to sign the former Thunder star.

If the Warriors weren’t the favorites to win the title heading into next year, they certainly are now.

The Thunder face an uncertain future. Do they rebuild? Do they trade point guard Russell Westbrook, who will be a free agent in 2017? Or do they use the cap room Durant’s departure gives them to acquire another player? 

Certainly, they’ll try their best to keep Westbrook around, but if they do, and if he doesn’t commit, the team risks losing both him and Durant for nothing in back-to-back years.

“Kevin made an indelible mark on the Thunder organization and the state of Oklahoma as a founding father of this franchise,” Thunder GM Sam Presti said. “We can’t adequately articulate what he meant to the foundation of this franchise and our success. While clearly disappointing that he has chosen to move on, the core values that he helped establish only lead to us thanking him for the many tangible and intangible ways that he helped our program.”

Oklahoma City could easily clear max room for another contract or multiple ones if it so desired — it’s nearly there already — but plenty of big names are already off the market. In fact, more than 50 players have signed at this point. We’ll likely know sooner rather than later how the Thunder plan to move forward.

Fred Katz covers the Oklahoma City Thunder for CNHI Oklahoma. Email him at fkatz@normantranscript.com and follow him on Twitter @FredKatz.