I read things like this--and I've heard/read about this issue many times over the past decade or so--and to the extent that major league teams are good for a city, the city should own them. Having wealthy, capricious owners who can hold cities hostage is bad on so many levels. Think about it this way: would you pay $100M to help a business out without getting some stake in that business, or at least a whole lot of guarantees that you'd be paid back? That is exactly what is happening with these teams.
It seems to me that that would be a lot easier to sell to taxpayers/citizens: "We're going to spend $600 M to own the Orioles" instead of "We're paying $600 M to the Orioles' organization in return for which they may not leave the city for now." Then make a handful of the trades/drafts/deals up for a vote, and if it ends up not working out, no problem: they can always sell the team down the road!
Note: I actually do see lots of problems with this proposal, and don't think it would fly for reasons beyond even those, but I don't know why I haven't heard [anything] like it.