Can we have an improvement to Kennen's energy issues, especially in the late game?

Note that this post is not about the laning phase, where he can easily use his passive to maintain energy.

It's extremely hard to utilize the CDR Kennen gets from his standard builds, because his abilities cost so much energy. This is an issue that similar AP carries don't suffer from, because mana is almost unlimited in the late game. He can't really proc his passive outside of ulting in the late game/while sieging and quickly becomes tapped, because energy regenerates almost 2x slower than shurikens spend it.

Electric Rush's cost also makes no sense. It used to be reasonable in past times, when he was one of the most mobile champions in the game, but with mobility creep, this no longer holds true. It's especially problematic when he's going in to ult, especially on objectives; he's often not going to get the refund, leaving him deep in the enemy team and possibly tapped on energy.

Scaling energy regeneration with level would be great.