The following is being posted on behalf of the Mercenaries team:
We know players are eagerly waiting for some way to use their excess coins. We’ve previously shared that we have a two-stage plan for that solution. We are nearly ready for stage one of that plan. In Patch 24.6, we will be introducing a new system that will let you exchange excess coins for a resource you can then trade for Coins for Mercs you haven’t yet Maxed. In stage two of our plan, this system will also tie into challenging …
Not exactly, they just state that they are splitting it into 2 parts. They havent mentioned anything about part 2 yet, so it may be a while before it comes out.