It's just a recognition that the distinctions between varying forms of fighting vehicle are disappearing more than anything.
M2 Bradley was going to have VLS silos in the mine boxes for carrying APS and potentially anti-drone missiles with SIDS anyway, so I'm not sure why you think a fighting vehicle can't have all of that and still carry people, tbh. Bradley already weighs somewhere north of 40 tons with the full BUSK and mine protection package, and the fancy CITV, so it's not like a 40-60 ton IFV is much different in transportation requirements anyway.
The optimal vehicle for future soldiers might be a single "omni-/multi-purpose fighting vehicle" (an "OMFV") which has something around 4-6 dismounts, a 50-75mm cannon firing HEVT and APFSDS with 40-60 rounds onboard, a 30-40mm airburst RWS for anti-drone defense of the platoon's air defense, top attack protection against 40-60mm artillery bomblet grenades and 120-155mm EFPs, top-attack/direct attack anti-tank missiles akin to Javelin (or better, SRAW), protection against its own main armament along the forward arc and 30mm APFSDS/125mm HEAT along the sides, possessing GALIX-like under-armor smoke/chaff/kinematic flares to confound mmW guidance and infrared seekers of guided weapons.
Of course RB301 isn't going to be that vehicle since it has to be built in a Bradley factory. OMFV might be closer, but RB301 is mostly just a Bradley with some volume shifted away around to different things; less volume on automotives and ammo, more volume on armor survivability and electronics, it seems. Bradley's turret is godawful tiny and the fact that they had to mount the -A3's CITV in so goofy a manner just proves that it's in dire need of replacement. While they're at it they can free up space by adding some meaty sponson motors like the MGV perhaps since the BUSK kits are essentially mandatory and Bradley's massive front engine is too anemic and the whole thing is struggling to go down hills, let alone up them, at this point.
I have no idea why you think the UT30 "lacks a coaxial" though. The .30 cal's plainly in the same spot as the Bradley's actual coax on the RB301, on the right side of the gun:
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It's the same turret as the Redback, except the Redback uses the manned MT30 (it's slightly wider), while the RB301 uses the robotic UT30.
