What if... omnistone granted two random keystones at once?
I feel like the biggest problem with omnistone is that it only has a decent comparative advantage over other keystones if you continually spam all of the keystones, the second you stop, it ends up being worse because it takes 40 seconds to replace which is often worse than stuff like electrocute.
Now, this is crazy, but what if it gave access to two keystones at once? This would give it a significant comparative advantage while still being fairly random. If you got some combo like conqueror and pta/lethal tempo it could be crazy, but of course there would be lackluster combos as well.
Another issue with the whole thing is being forced into the inspiration as primary tree, which, while not that bad, is pretty suboptimal for a lot of champions would might have wanted to use omnistone. This change would further make up for that.