The author of that paper obviously did his homework. Impressive. I wonder if he's presented it to any of the decision makers yet? But realistically, I don't see them opening up that old high line. They might have to think of other options. The residents, rightly so, will oppose it, & in this case I don't think the nimby tag is entirely fair. You can see clearly, in some of the pics, that entire neighborhoods were built up around the stations by new suburbanite commuters way back when. But this is 60 years later & it's a lot more crowded now. Some of those neighborhoods simply wouldn't be able to handle the extra traffic & population bump that would go along with that.
If they're looking to open it up all the way out to the Rockaways, they can have a limited number of stations, & finally dismantle the remains of the rest as disheartening as that may be to the proponents. Frankly I'm surprised there haven't been tragedies already with those abandoned staircases. They don't have to scrap it entirely, just bring it back in a limited way. Maybe they can call it the Rockaway Limited.