a 50cal is still on the low tier of vehicle grade firepower though. There's a much wider range of light to medium vehicle grade weapony. Besides, carrying any significant amount of ammo is gonna be bulky, so that has to factor in.
and i said "like" the picture, not specifically the picture. Doesn't have to be any specific gun, could be hardpoints for all it matters. But something of that overall structure could concievably interact with its environment and fire its weapons at the same time if need be, has enough room for decent ammo storage, can mount heavier armor, move faster, and has enough room to mount countermeasure type systems, and probably include some backup weapons to boot.. It has more surface area granted, but not that much more than a medium armored vehicle.
Exosuits increase infantry survivability, but until you get to starship trooper level of exosuit design where they are jetting around popping off mininukes, i don't think they are gonna make vehicle scale obsolete.
At any rate, neither of us are gonna get 2 legged or 6 legged tanks any time soon. What we are gonna get is load bearing up armored infantry, more advanced conventional vehicles, and lots and lots of robot drones of every stripe.