> Do they seriously think a fee applied on retroactive sales and revenue numbers would be accepted without issue from them?
Unity have not proposed a fee on retroactive sales. They have proposed a from-this-point-forward fee that applies to new sales/installs of any game made with Unity, including new sales/installs of back catalog games.
Sales and installs don't happen at the same time. If I buy a game once on Steam, I might install it on any number of unique devices. Per the Unity FAQ, every one of those installation events results in an additional bill for the game's developer.
In other words: This is absolutely a retroactive rug-pull on new installs of old sales.
Update: Because of the way they're rolling this out, the only way to avoid the retroactive license change is to immediately stop using Unity's development tools. If I were running a game studio, that's what I would do.
Unity have not proposed a fee on retroactive sales. They have proposed a from-this-point-forward fee that applies to new sales/installs of any game made with Unity, including new sales/installs of back catalog games.