Laser Pistol vs All Predecessors

If (as argued elsewhere) the Heavy Cannon is the best primary squad weapon at the very start of the game, what to do when the Laser Pistol is available?

Unfortunately I think the Laser Pistol is so powerful that it immediately displaces the Heavy Cannon as the primary combat weapon, and forces it into a support role. The Heavy Cannon will languish on the shelves, at least until much more heavily armoured enemies arrive on the scene.

As a support weapon its use will be restricted to clearing terrain (with AP and HE), and delivering explosive rounds (including against terrorists). On a terror mission, it might be partly restored to its earlier value to minimise "friendly fire" against civilians.

If Mutons (or Ethereals) were to appear before the advent of Laser Rifles, then the Heavy Cannons might come off the shelf and be distributed to the bulk of the troops. Otherwise, the Laser Pistol significantly exceeds the Heavy Cannon in general-purpose firepower, and far exceeds it on versatility, weight, space, ammo, speed and flexibility.