I know these are old comments.
Don't want to sound ignorant - too late - but could you 'Namer' an Abrams? Understanding the Merkava has the rear hatch for troops already my guess is too complex to do to an Abrams.
Not easily. Abrams has the engine and transmission in the rear, Merkava in the front.
So you'd have to start by flipping the whole chassis around back-to-front, just to get a large volume in the hull for the troop bay.
Then you can build the superstructure to let the grunts stand up inside, ~6'6" to 7' between deckplates and internal ceiling. 6"+ from deckplates to bottom of hull, for the v-shape. 16" ground clearance. So we're talking about something ~9ft tall to the top of the back deck.
Here's a simple question--in the 21st century environment with a focus on assymetrical warfare, does every IFV really need a big gun in a turret?
With the off-the-shelf (or nearly so) solutions available, why not mix turreted IFVs with fewer seats with turretless APCs with more seats (CV90s and Armadillos, for example, or a Puma-based equivalent) to carry the same number of troops in the same number of vehicles? The turretless APCs would still have remote weapons stations up to and including .50 cal MGs and 40mm grenade launchers and there are any number of solutions to provide additonal precision fire support, for example, a Griffin mini-missile derivative or a more powerful Switchblade armed, disposable UAV.
If the focus is on asymmetric warfare, does every vehicle need a big gun?
1) yes, every vehicle needs a large gun, anything visibly less well armed would be isolated and attacked in a COIN situation. Also, if your vehicle in contact has all the tools on it, you cannot have some asshole in the rear deny your request for (insert weapon type here). So each RWS is likely to have a laser dazzler, an LRAD loudspeaker, both an IR and visible light searchlight, and maybe even one of those microwave "pain rays" to make people stop (I'm not sure if the microwave can scale down small enough and still be safe).
2) you don't EVER want to split fireteams between vehicles. That's the single greatest failure of the old Bradley model, and it's why the new Mechanized Assault platoon has 6x Bradleys instead of 4x. They're only packing 4-5 dismounts per Bradley so that each fire team stays together, one fireteam per vehicle. (The old model was 1.5 fireteams per vehicle, so 4x Bradleys carried 6x fireteams. Which meant that as long as the entire platoon stayed together you'd be more or less okay when everyone debussed, then the 3rd squad would organize themselves from the split fireteams.)