I heard new EMU's were in the works , MLVS cannot replace all the Arrow cars and there expensive to run offpeak...
They have talked about new EMUs but my understanding is that Weinstein is not in favor of them, nor is Simpson. For the same reason that Warrington wasn't in favor of them. MLVs can replace Arrows to NJTs level of acceptable on every line but the Princeton Dinky which will eventually be converted to a bus like it should have been 20 years ago.
To your point of view and my point of view, obviously shorter Arrow trains off peak make more financial sense to operate than a 10-car or 2-car long MLV train. However! That is not the way NJT thinks. If NJT was thinking properly, they would be switching cars off of trains at their yards to operate shorter trains off peak rather than running an 8 car long MLV train with 2 cars or 1 car open thus pointlessly wearing out equipment for no good reason.
NJT sees the FRA's requirement to treat MU cars as locomotives for inspection purposes as an unbearable burden. So they don't bear it. This is why the Arrow IIIs are the oldest cars in the fleet, and why 70 of them are being retired in short order. They will be used on the Gladstone branch and possibly some Trenton Express trains and thats it. Naturally, using them on Trenton Express trains is the biggest, dumbest waste of the equipment possible. Express is where locomotive hauled equipment is more useful than on the hilly, highly local operation found on the M&E.
In addition, NJ Transits insistence with their Unions is that a train, regardless of its size, requires three crew members at minimum- an engineer, a conductor, and a brake man. Their insistence on this silliness is why the Princeton Dinky is such a gigantic waste of money. Operated by a motorman alone with POP fare strategies, it would be as financially sensible as any other light rail operation. But when you need three crew members to operate 1 car long, no locomotive train the 3 miles from Princeton Junction to Princeton, it becomes financially ludicrous.
The Arrows should be able to operate with 3 cars and two crew members. Then they might be financially sensible enough to justify their operation over running a longer, closed car train set.
Arrow IVs or MLVMUs might happen. Anything is possible but skiing through revolving doors. But as I stand here today and watch management, probably with more diligence and realism than you, I say they aren't going to happen until NJT becomes a sensibly operated organization, which at the current pace will come on the day a snowball survives 48 hours in hell.