MBTs maybe, but light tanks still have a bunch of uses.
This mind of flip flop did actually happen during the Cold War when heavy tanks were phased out by both sides and especially by the French and Germans whose AMX-30 and Leopard 1 were less thickly armored than the M48 Pattons they replaced. The reason was the development of ATGMs which could punch through M48 level armor extremely easily and steel armor thick enough to counter them was impracticable heavy.
By the time AMX-30 and Leopard 1 were replaced with Leclerc and Leopard 2, both successor tanks had gone back to being heavily armored. The reasons being the development of better engines, explosive reactive armor, and composite armor capable of defeating ATGMs.
We may be on the verge of another inversion of protection vs size and speed, but one conflict is too little evidence to make that kind of assessment. The issue with phasing out the MBT is the question of what you replace it with. Removing them from an army entirely leaves a gap in a maneuver vehicle that can bring a lot of firepower to an objective quickly and have the durability to withstand fire.
This mind of flip flop did actually happen during the Cold War when heavy tanks were phased out by both sides and especially by the French and Germans whose AMX-30 and Leopard 1 were less thickly armored than the M48 Pattons they replaced. The reason was the development of ATGMs which could punch through M48 level armor extremely easily and steel armor thick enough to counter them was impracticable heavy.
By the time AMX-30 and Leopard 1 were replaced with Leclerc and Leopard 2, both successor tanks had gone back to being heavily armored. The reasons being the development of better engines, explosive reactive armor, and composite armor capable of defeating ATGMs.
We may be on the verge of another inversion of protection vs size and speed, but one conflict is too little evidence to make that kind of assessment. The issue with phasing out the MBT is the question of what you replace it with. Removing them from an army entirely leaves a gap in a maneuver vehicle that can bring a lot of firepower to an objective quickly and have the durability to withstand fire.