Get ready for a huge political distraction for the next two years (and then seven more after that if we win the global bid). I expect a state referendum will be held and our bid will be voided.
As for the bid itself; if we can do it in a cost-effective way then bring the games on!
I doubt that a referendum will stop it, for a few reasons. First, we're 18 months away from the 2016 election, and that's not a lot of time to pull something like that together. You need an actual campaign operation with money for TV, print and radio ads to pull it off, and you're up against a group with national backing and a lot of private money and support.
Second, Boston 2024 has made it pretty clear that they consider their budget to be only $4.5 billion in private money. All public infrastructure spending is considered external - the Games will be served by projects already on the agenda for MassDOT and others. A referendum can only affect public money, so it would have to be worded in a very petty way (public money will not be spent on any project which could conceivably benefit Boston 2024). That touches projects a lot of pols are invested in already.
Third, referenda in Massachusetts can only make recommendations, not policy. A state government concerned about its reputation (especially if Charlie Baker endorses this project tonight - welcome to the job, Charlie!) is going to find ways around anything even if it passes. A referendum in Boston might be different, but Boston's infrastructure commitment isn't nearly as important as the State's.
Bottom line: it's tough to have a vote on whether a private non-profit can hold an event, and I think this ship has essentially sailed. At least until 2017, this is happening.
FWIW, I was pretty convinced up until 6:30 that it was going to LA. Pleasant surprise.