I think based on transformers i've seen for EMU you can estimate a loss of 16-18 seats per car.
If you shortened the double level section, and had a longer mezzanine, you could make up some of those seats in the mezzanine area. It also depends on how they orient the transformers. If they orient them transversely you lose fewer seats than if they orient them longitudinally.
Another thing is that if they go with 2 trailers in between the power cars, those few seats lost won't make much of a difference. They may go another direction entirely and come up with something i'm not thinking of, though the possibilities with the MLV form factor have limitations due to overall weight, how the weight is distributed, and where you put doors and pantographs and HVAC and dynamic brake grids (yes you'll need them stopping a 10-12 car MLV train), and truck design.
It is possible, but what the end product looks like (layout) may be radically different than the current coaches in service
Next stop the square, journal square station next!