1) It is much easier to demolish a building than it is to rebuild it. It's possible that there would be a lot more demolishing than there is rebuilding. 2) We can assume that a significant number of people would chain themselves to buildings or respond with physical violence when the feds of the time come in to demolish their property. 3) Due to changing sentiments commonly held by police officers and general loyalties, we can assume that local law enforcement would often not be willing to fight against these locals for the cause of destroying their property. Therefore, the military would need to be called in to secure many of these sites. 4) Legal actions would go up to the SCOTUS and a conservative SCOTUS would likely not allow large scale demolition without up-front reimbursement (eminent domain). Democrats would presumably try to pack the SCOTUS in order to get it to enforce this. The kinds of people who would support large scale demolition without upfront payment would not have what it takes to serve as respectable judges, by which I mean, they will likely stick their foot in their mouths every time they write an opinion and further piss off the people they have already dealt grievous harm to. 5) In order to fund this event, we would need trillions in new taxes and new stimulus, yet America has already printed an unprecedented amount of money recently. Especially in the near future, printing enough money to attempt a green new deal would almost surely lead to rampant inflation, which would destablize the world economy and other politics because it would make the dollar useless as a currency peg. 6) Each setback in the demolition process would obviously be met with murderous rage and new levels of political and social extremism, leading to currently unforeseeable events on top of the things mentioned here, which IMHO are completely foreseeable at this stage. Basically, I don't think I'm exaggerating when I say that the green new deal, if it were ever seriously attempted, is capable of starting world war III. Once the dollar is no longer usable as a currency peg, all of the current world order's enemies will make their moves, people in America would be shooting each other in large numbers, the military (which is majority Trump supporter, yet duty-bound to obey the President) would probably fracture, the SCOTUS would be seating 15 *******s who couldn't even pretend to be reasonable, etc.