They can still [i]encourage[/i] certain weapon types each season, but Bungie should allow us to choose which weapons we make Anti-Champion, like so;
This Season (fictional) all Primary weapons can be Anti-Barrier, all Special weapons can be Anti-Unstoppable, and all Heavy weapons will wreck Overloads.
Then just flip it next season, and so on. Keep adding mods like Particle Deconstruction to make certain options more attractive, but let us decide which weapons we actually can use.
I can see them maybe adding elemental anti champ mods, that make any matching damage type have and AC effect. something like solar stuns unstops if you have the mod on, arc Pierces barriers, and void suppresses overloads. Stasis i can see them maybe adding a 4th champ type for, maybe a medic style champion that doesnt do a lot of damage but has a high health and slowly heals the non champion enemies within range. Stasis could stun that champion.
Something like this could allow players to spec into specific elements and stack really well with the elemental well mods they introduced.