Having transit through areas with some density could be better than constructing transit through a giant reservation with nothing there based on expected ridership. I am not an expert on this, but judging from the online maps, "At Grade" Blue Line through Revere from the left turn at either Wonderland or Revere Beach will be difficult, since there aren't many free space to do so. There would be a lot of demolition of homes, which isn't great based on cost, since there would have to be imminent domain. Plop some stations scattered around Central and/or Northern Revere, go around the giant reservation and then you reach Lynn. Redevelop the area with apartments + businesses around the T-Station, there you got more ridership. It would be cool to have Everett and Chelsea portion of land be served by subway. Maybe create another rapid transit line? haha, maybe not. Well, I'll just stay with the Blue Line at the moment.