Was it? My recollection (which may be off) was that they had attendance issues for years before they finally moved. I may be way off on that, though.
From what I've read, the 1994 strike really killed the team and the fans were bitter about losing their best season ever. They also played in one of the worst stadiums in the league (built for the Olympics, not for the Expos) and the Canadian economy at the time had no appetite for funding a new one. MLB also allowed Jeffrey Loria to buy the team, not invest any money into it, and then sell it back to the league (and then win a World Series with the Marlins). Finally, MLB took over the team, forced them to play games in Puerto Rico, and wouldn't allow them to do the same minor league call-ups that everyone else got to do during a pennant race. MLB pissed on the market for 10+ years before moving them to DC. It's not unlike what they've allowed to happen in Oakland. The difference is that Montreal is a huge market with the economic ability to support a team compared to Oakland which is a pretty small city whose footprint is cannibalized by the Giants.
The thing about the Bay Area is there's a lot of strong subregional identities, and Oakland/East Bay is one of them. There's about 3M people on the Oakland side and despite attendance they love their As. But what has happened to Oakland is more than just it losing its sports teams. There's been a huge cultural shift, especially in the last 15 years with the movement the tech industry caused. A lot of things that made Oakland Oakland disappeared (aside from crime but I digress). The people that moved to the East Bay/Oakland the last 15-20 years don't care about Oakland. SF/Peninsula is the money side. Why the Warriors left. They want to be more associated with the SF brand and people look to SF cultural things/sports. And those that cared about Oakland moved to inland CA or left the state entirely. The military used to have 4 or so bases in the East Bay alone and all have been shut down since the 90s, and those people had become hardcore Oakland people. Montreal is a bigger market at 4M people and is a standalone city that doesn't have to share any shine, so they have that going for them but I feel like if Montreal was truly viable market for the MLB to move back to right now the As would have been in consideration. It's better for them to be in a market half the size of Montreal, albeit a semi-glamorous one. Vegas is like a desert Miami at this point.
Baseball fans in Austiin would welcome a team. Not sure if there are enough of them. MLB probably would love having a team in Austin. Longhorns have a lot of pull in Austin. If there is an Austin team, it won't be in Austin. Not being in/close to a downtown has been a problem for several teams. Round Rock Express was great for me when I worked in Austin and the team was affiliated with the Astros, but I worked in North Austin. Going north and south use to suck in the Austin area and probably still does such that I just don't think an MLB team could work that isn't in Austin. Regarding San Antonio, I just don't know if they have the potential corporate backbone Austin does.
Awesome post. Having some familiarity with the Bay Area, I think you're spot on. For both Oakland and Montreal, the issues were not as simple as "fans stopped going" because there were a lot of reasons why fans stopped attending. I think Las Vegas is a talisman for all of the leagues. Here is the metro population of all areas with at least one team in each of the big four leagues: New York: 19.6M Los Angeles: 12.5M Chicago: 9.5M Bay Area: 7.7M Dallas: 7.6M Philadelphia: 6.2M Miami: 6.1M Washington: 5.5M Phoenix: 4.9M Boston: 4.4M Detroit: 4.4M Minneapolis/St. Paul: 3.7M Denver: 2.9M Las Vegas' metro population is 2.2M and its chief economic driver is an industry that none of the leagues would touch 10 years ago. I don't think MLB is putting a team there to build a strong homegrown fanbase; they probably want to be there to attract a large number of visiting fans to every game (thus the lowest-in-the-league capacity for the stadium) and lean even harder into gambling. It's crazy to think that the NBA is going to be the last to the Las Vegas party considering they broke the seal with the All Star Game 20 years ago. This is also an argument for why Houston (7.1M) should have a hockey team .
I remember like MadMax, but looking back at the attendance, it was basically meh, but went disaster with a terrible team and talk of relocation. Arguably better fan bases than Miami or Tampa. Really hard not to blame Loria and can't believe how he conned his way into millions by basically exchanging the Expos for the Marlins, and then a billion selling the Marlins.
