You should be able to upgrade things, with elixir and dark elixir. All it would be is about 1/4 more the price of the original loot to upgrade it, but in a different loot. Be it gold, elixir, or dark elixir, I think this would be a cool feature. For example, want to upgrade walls but don't have enough gold and A LOT of elixir, you can just press "Upgrade in Elixir" and it will upgrade. However, you are still allowed to upgrade things with there original loot and price if you wish. Unlocked at Town Hall 11.
