I don't believe this is true, AFAIK the majority of their revenue comes from their in-game advertising business, not from licensing the engine.
- 30% of revenue from Create Solutions (ie engine licensing) - 61% of revenue from Operate Solutions (ad platform, IAP, multiplayer, build server, VOIP, CDN, analytics) - 9% from strategic partnerships
Although they are known for catering to the indie developer crowd, a bulk of their revenue is from a relatively small number of companies (~120).
https://www.statista.com/statistics/1270474/unity-software-r...
So, they can open still open source it? I mean, open sourcing it would allow competitor to use the same code, but given it is not the same brand and not possible to release to consoles or stores, they could still keep most of their revenue, right?
One of the things devs like about Unreal is that the entire codebase is just there to look at, so you can debug any bugs yourself and even add features to the engine that you specifically need for your game. Meanwhile Unity is a black-box blob that you can’t neither debug or extend, and all you can do is yelp in the bug tracker or the forums to get unnoticed.
I don’t know any actual numbers