"You want the benefits of the metro region, you have to do your fair share to support it. Your town's share of new transit-accessible housing units is XYZ. If they're not built or under active construction by 2030, you lose all local zoning/approval of multi-unit housing other than enforcing the state building code. Didn't want a 20-story tower with zero parking next to your train station? Shouldn't have been selfish and isolationist."
Realistically, I think a useful addition to the law could be an instruction for the MBTA to develop housing on parking lots it owns, focusing first on communities that don't comply with the law. (That doesn't help with communities that don't have stations, but it's a start.) Make it a carrot-and-stick: if you work with the MBTA to built TOD, the state will assist with expanding schools and other public services to match increased population. The MBTA already works with some areas for TOD - see slides 28-31 from yesterday's meeting:
https://cdn.mbta.com/sites/default/files/2024-04/GM Report to the Board 04.25.2024 v7a.pdf