None of the stuff mentioned above will ever see the light of day. Not in our lifetime. The ideas make very good sense, and not to a rail buff, but to anyone who has a desire to provide a reliable public transportation system to areas that lack it, for the sake of the environment as a whole, and not as a solitary problem. The orginal Central Branch should have been first considered before opting for the third track on the mainline. NIMBYs put aside, the former Central Branch would be a less intrusive option, as minimal property would be taken, if any, to create this line. It would also serve a highly congested area of Nassau county which is truly, half way between the mainline and Montauk branches. It would by default, serve NCC, Light House Project, and several other areas that don't have reliable public service. The problem? The tracks were gone before these neighborhoods were built. No train has past there in decades, and no matter what some say about powerlines and what dangers the present, they are, regardless, a quiet neighboor. Nobody in Levitown, East Meadow, or most certainly Garden City, would allow such a thing to fly. SO..... a few people in Carle Place, Mineola and New Hyde Park will or might, have their properties taken to build a third track. Why? because the tracks are there, they always have, and will be the less "vocal opposition" option on the table.
A connection between Hempstead and the West Hempstead branch will not support the cost associated with building the line in the first place, although a "North South" branch is greatly needed regardless of what anyone says. If you build such a thing, New ridership would be created in a heart beat. Problem? location. A North South branch would be better on route 110, not Hempstead. And a single track operation would still limit capacity. Thinking "out of the box" however, no street crossings would be really necessary in such a project. Elevating lines, while more expensive, is still a better option. The stuff that really needs to be focused on is: Double tracking the mainline all the way out to KO and further to Riverhead. Electrify ALL branches, including out to Greenport and Montauk, Eliminate 251 territory, and create a bypass to Jamaica. And of course... Finish the ESA project before the next Ice Age comes. The 3rd track on the mainline is necessary, but only if you add capacity out to KO. The present Central Branch as has also been mentioned, is also on the list of "possibilities" for expansion, by electrifying from Beth to Babylon. The rest is all history. If the old LIRR would have saved them all, then we could have a totally different map today. But it won't ever make it back with the very NIMBY minded population of Long Island. Lastly, NJ Transit is able to expand because New Jersey is not locked by water on all four sides. It also, while highly populated, is not as cramped as Nassau county and western Suffolk county are with people, and limited space. Likewise, some of their expansion plans involve reactivating passenger service to lines which already exist for the most part, or as in the case of the line to the Poconos and Scranton, not as populated as eastern NJ. Central and south NJ are very unpopulated. Just drive south of exit 8 on the NJ turnpike, and you got squat. Expansion in mileage is logical for NJ Transit when you take into consideration of the geography of the state.
The LIRR needs to expand by first fixing the undercapacity it has on it's present lines, and bringing the entire RR up to "today's standards". Look at all the potential they have out east? Yet it still remains underserved, streets continue to get crowded, and more people continue to move east. Just because the map doesn't get bigger, doesn't mean that there is no room for expansion. There is much to still do that is much more important to our local economy.