what do we do with the champion shards?

From the FAQ:

I own all of the champions. What can I do with champion shards?

At launch, you’ll be able to disenchant extra shards you find in chests for champion essence. We’re currently exploring ways for players with every champ to use the shards they earn but we haven’t settled on the final form of the plan yet. As Hextech Crafting and loot continue to evolve throughout the season, we’ll keep you posted on any new features we add.

wait for new champ to come out use it for that idk