When it started, we had 4 chests available. We've gained 1 per week. I currently have no chests available and have received 10 chests total I think. That implies that it has been 6 weeks, not 6 months.
They're working on it. Maybe it won't be super fast. Given that the average player would only have a maximum of 10 chests by now (with probably 3-4 unopened due to keys - my current spot), it's unlikely anyone has more than 2 or 3 champion shards that are currently useless to them. Assuming those shards don't provide sufficient essence for whatever Riot comes up with, then there's no harm that they haven't released it yet.
E.g. say each champion shard averages 300 essence. Let's say Riot decides to release the ability to spend 2000 blue essence to re-roll a permanent skin shard in to another permanent skin shard. You'd need an average of 7 champion shards to do that, which most players would be a LONG ways out from (and those unlucky enough to get a lot of champion shards wouldn't have the 3 skin shards yet to reroll in to a permanent to use this reroll on anyways).
So just be patient. They'll get to it eventually. You can also save the shards and reroll 3 in to a guaranteed champion you don't own (i.e. when the new champion is released, immediately get it for free).