This is already the case. People are generally buying those games for the licenses and then using mods. For example, you can buy Falcon 4.0 on Steam, but the on

This is already the case. People are generally buying those games for the licenses and then using mods. For example, you can buy Falcon 4.0 on Steam, but the only reason to do so is to legally play "Falcon BMS", an otherwise standalone free game using Falcon 4.0 assets and code.