Well, I can't say that the writing hadn't been on the wall for some time, but certainly since the beginning of last season. I remember reading about extremely low attendance figures in 2022 and 2023, and while the reverse boycotts helped them wind up above any of Ohio's minor-league teams in 2023 (10,000 per game), they're still only 30% above the A Dayton Dragons, and 30-35% above the AAA Columbus Clippers (the Toledo Mud Hens also have more than half the A's attendance, at 6000 per game). It's going to be hard to sustain a major league payroll on that.
That said, from everything I've read, the root cause is the owner essentially giving up on the team and the city. I'm not keen on the whole relocation thing, nor the "we always need a new stadium" thing, and Oakland has been the most unfortunate city with sports relocations in the past decade. I know it's not an entirely new phenomenon, and the Philadelphia/Kansas City/Oakland Athletics are perhaps the prime example of that in baseball, but nonetheless, I'll always favor a "sell the team" approach before a "relocate the team" approach.
Didn't know that Sacramento was going to be the interim locale though. Will be interesting to see if many people show up for the games there. Looks like the AAA Sacramento RiverCats got about 5200 fans per game last year.