A tank is protected direct firepower. Your definition neglects light tanks, which have their uses (primarily in air mobile operations). A Merkava is a tank beca

A tank is protected direct firepower. Your definition neglects light tanks, which have their uses (primarily in air mobile operations). A Merkava is a tank because it's point is the firepower, not troop carrying. A Bradley is not a tank because the point is the troop carrying, not the firepower. There may be talk of tanks going to 152mm, but that's not a talk for NATO. NATO doesn't use 152mm anyways, and the predicted next iteration is 140mm. Heavy ERA is possibly sufficient against Sabot, and APS is looking at being able to intercept sabot is well (mostly in the form of knocking the penetrator down. There's nothing technically stopping an IFV from carrying a MBT grade gun (Styrker MGS carried gun equivalent to the original M1). Similarly, there remains interest in use of hyper velocity missiles for anti-tank use (which gets up to APFSDS speed, but doesn't need the gun to do so. See KEM/CKEM. And many of the IFVs use APFSDS ammo (Rheinmetal makes it).