Those are already available as a drop-in for existing tanks -- the Israeli LAHAT is available in 105mm and 120mm versions, and is in service with two NATO armies (Germany and Croatia). It's a good piece of kit for what it is -- but most armies want to keep their tanks moving and instead fight the long-range missile battle with things like TOW and Javelin.
The Canadian Army, on the other hand, seems to be in denial that anti-armour weapons are even needed, and seems to think that the 84mm recoilless rifle represents the peak of armor defeating technology. Which isn't quite the same lesson that the Ukrainians have picked up.