To steer Ron back to topic:
The above cited early legislation in which the Legislature intervened in zoning has to be put in historical context. The Legislature was controlled by the so-called "Yankees" (a very broad brush term, but we'll leave there for now). Boston had come under the control of the Irish, whom the legislators regarded with a mixture of contempt, racism, envy and alarm.
The spirit of legislative intervention in those days was fueled by the paternalistic belief that "it is good for them, whether they like it or not, the ignorant rascals".
No doubt, the geniuses behind this proposal have the same paternalistic attitude toward the "unenlightened". What's missing this time is the powerful motive of racism (individual or collective) that made the earlier efforts possible.
In short, the Legislature has the power to do it, but probably not the stones.
P.S. As an example, G.L. c. 40A, s. 6 grandfathers lawfully commenced uses and buildings that were in existence at the time a zoning change goes into effect. Anything that requires a teardown is a taking that will require the owner(s) to be compensated. Those of you with dreams of demolishing ToC: forgeddaboudit.
P.P.S. To be precise, Boston has its own zoning special act. However, the grandfather protection in 40A:6 is analagous to that in Boston's act.