out of all the concepts so far i think the one that jumps out at me the most is the weather equalizer for a few reasons. First of all there are many different directions this cap could go. Also this is the biggest part of the metagame right now yet two weathers have gone relatively unexplored due to the lack of benefits compared to other weathers.
this would allow us to find the most effective way to incorporate hail and sun into threatening forces in the ou metagame rather than them mainly being an easy way to take the weather advantage away from a weather team.
this cap could either look to develop a monster hail or sun threat like tornadus-t in the rain or life orb sheer force landorus in the sand. this would show us what makes a threatening poke that much more effective in a certain weather- whether its the ability, moveset, typing or a perfect combination of all 3 that is just tailor- made for that weather.
another way this could go is a poke that could function well in hail or sun and totally check and ko opposing weather starters. this would make hail and sun more useable simply by having an extremely good strategy of winning the weather war. one example that comes to mind is a scarf genesect+focus sash dugtrio combo on a rain team. genesect's u turn threatens tyranitar and abomasnow and dugtrio can trap and ko ttar and ninetales no problem. some sort of way to give sun and hail starters a better chance at outlasting politoed or ttar would solve a major problem as to why they aren't used more in the first place.
anyways this is mostly looking ahead but i think it shows how this topic could lead to many interesting opportunities and how it really applies well to the current ou metagame