As someone who has lived in New York for 50 years, I doubt that MSG will actually be forced to move anytime soon. Political pressures will prevail, and there is likely to be a new vote by the city council sometime in the future giving MSG a further extension.
The goal in forcing MSG to move is to rebuild Penn Station, which lies under it and is very cramped. But even if MSG were forced to move 10 years from now, I have little confidence that the government would use the opportunity to rebuild Penn Station in a timely manner.
As you can see, I have become a thoroughly cynical New Yorker, shedding my gentler and more optimistic roots from my childhood in Connecticut. I flat-out predict that MSG will still be where it is today 20 years from now. In fact, it is more likely, IMO, that Anthony Weiner will be elected to office in the next 20 years than it is that MSG will move.