You can already exchange currencies indirectly. For example, you can buy Insta–Progress to get some Green Coins and Blue Coins from the extra rewards you claim. You can buy Mystery Boxes with Green Coins or Blue Coins and open them for other currencies. You can feed the Dragon of Wisdom for 1 Blue Coin each time. And so on...
You can already exchange currencies indirectly. For example, you can buy Insta–Progress to get some Green Coins and Blue Coins from the extra rewards you claim. You can buy Mystery Boxes with Green Coins or Blue Coins and open them for other currencies. You can feed the Dragon of Wisdom for 1 Blue Coin each time. And so on...