Please do a search on these forums - plenty of threads with responses from DTG. Basically more work than it was worth to do so - but do search if you want more details.
DTG has said that it would be quicker and easier to build the route from scratch than to even try to preserve it. NEC went one direction in development whereas the other routes went another, better way. I reckon we’ll see NEC come back in one way or another relatively quickly. DTG are aware that there is a lot of demand for Amtrak to be in the game.
NEC won't be coming to TSW2. However, Sam has mentioned they would like to do another Amtrak route, so maybe we'll see something similar further down the line. Nothing confirmed as yet though
At a guess, I would suspect they'll do the section north of New Haven where there is actual high-speed track and the Acela Liberty can stretch its legs. DTG is very into high-speed trains lately.
Or you know they could also do the section that just got recently done between Washington DC and Baltimore for Train Simulator 2021, which also has a good chunk of high speed running.
125 may have counted as "high speed" in the Seventies, but not today. Eastern RI/southern Massachusetts has the only sectors of the line certified as Class 8 (above 125 up to 160mph). Westerly to Kingston - 105 mph Kingston to Cranston - 150 mph Cranston to South Attleboro - 70 to 100 mph South Attleboro to Attleboro - 125 mph Attleboro to Mansfield - 150 mph Mansfield to Back Bay - 120 to 130 mph
To put is simply, NEC is not compatible with TSW2 and it is easier to create a new route from the scratch then to work on this one. Will the ghost of NEC ever leave us be or will it be haunting us forevers?