Will it matter though? They signed their death sentence the moment this original proposal got the go-ahead.
As some have already mentioned the trust is gone. I imagine just the knowledge that the company can do something like this is enough to deter customers. Why would you want to build your game and make your living based on an engine with this uncertainty in place?
I for sure will continue my project on Unity since it's not for sale and it gives me time until I finish it to decide if I'll sell it, and no matter if I do or if I move to another project then I'll switching to another engine. If I decide to sell my current project that means making a full game, but all current advances would be ported.
But I think, even if the trust is already broken, as long as a contract per version is maintained, devs (including myself) can feel secure since it would prevent Unity to mess around currently in development projects.
Most devs I see on Twitter want to at least release their currently in development games before switching to another engine or take their time to study of instead rushing due to the emergency, so expect many to stay in Unity for a while if they roll back.
But yeah, most are definitely moving away sooner or later.
They need to not charge anything at all. That's my point.
Any "update" they have that ends in anything less than a full withdrawal of the fee will kill the company. If not immediately it will die a slow bleeding death over the next 3 years or so.
They want more money and current business model isn't enough. Devs are ok with paying more as long as it feels "fair"... They just have to come out with something that makes finantial sense for all parties.