Is the MBT going the way of the dodo? I doubt it.
While high-intensity conflict may not be our focus in the future (it‘s bloody expensive to equip for, so we‘ll situate the estimate and eliminate it as a concern), the Americans and the Brits won‘t lose their focus as easily. They also won‘t forget that you can‘t knit tanks overnight.
Even in lower-intensity conflicts, if you want to drive the infantry onto the objective, they will need mobile dir fire sp with characteristics similiar to the MBT - excellent protection,high speed, and significant firepower. The LAV III probably can‘t carry the additional armour and the 120 gun and still maintain its mobility.
Until the infantry has its own direct fire sp in the form of a weapon which can kill tanks as effectively as a tank, armd sp will be reqr. At present, the best weapon for killing a tank is a kinetic energy weapon - i.e., a sabot. That kind of energy requires a big gun. A big gun draws lots of en attention - so you need mobility and protection. Ergo, a tank, not a recoil-less rifle.
The MBT is the strongest player on the battlefield, particularly in the modern configuration which balances protection, firepower and mobility. It is the ideal weapon for killing infantrymen before they dismount their AFVs. It is also the best weapon with which to kill other tanks -- particularly if you are on the offensive. (A TD may be fine in the defensive, but it is pretty useless on the move.)
The M1 will be around a long time. We just won‘t be driving it.
What could replace it? How about a ten (or even twelve) -wheeled LAV variant with additional armour, a more powerful engine, and a 120 gun with some form of active suspension for gun platform stability? There are obvious trade-offs, and it may not be much cheaper in the long run. But it may be a more acceptable alternative than either adopting M1s or foregoing dir fire sp.