As an Infantryman, I can't argue too much with a tanker over the "best" features of a tank
. Looking at it from slightly outside, however, a "fourth generation" tank or whatever we will be calling it will have all of 2Bravo's characteristics, but with the following factors driving the technical evolution:
1. Need for strategic/operational mobility. No matter how you slice it, a 70 tonne tank is really the end of the line. Future fighting machines need to be transported across oceans and continents, and in theater, be able to do long road moves quickly and quietly (relatively speaking) to keep the enemy off balance. Smaller and lighter vehicles are a must. Improvements in fuel economy and suspension technology also reduce the size of the logistics train.
2. Tactical mobility in close/complex terrain. We can argue about the virtues of tracks, wheels, legs, rotors etc., but any future armoured vehicle will need to get around, and quickly. Given the urbanizing character of today's world, there should be at least some thought into how AFVs can operate in a 3D environment.
3. The supression battle. Given the identified need to defeat the enemy through fire, future armoured vehicles will need multiple weapons and lots of on board ammunition. There is also on board room for various natures of ammunition, ranging from through tube missiles to defeat targets at long range to "dumb" HE rounds for bunker busting, allowing the future AFV to attack a wide range of targets. This also ties into factor 1, since a generous ammo rack means fewer trips to the ech to "bomb up".
4. The network battle. Future AFVs will be able to operate as tanks, DFSVs, perhaps some limited AA or AAA and as SP artillery if they can tap into information from off board sensors. The tank essentially morphs into the MMEV in this scenario
IF any one vehicle can be said to incorporate most of these characteristics today it is the CV 90120. I understand 2Bravo's reservations about RPGs and other stand off weapons, but that is why Infantrymen accompany tanks, to deal with annoying problems like that. The future AFV will be part of a future combat team, and the team commander will (hopefully) have the ability to pick up targets at long range, shape the battle by fire and manoeuvre the team to create a KZ "on the fly". I would hope the idea of stand up tank battles is somewhat of an anachronism, but proper doctrine and TTPs should give us the edge.