Rule 4: get fucked by better and cheaper products (Unreal/Godot)
Rule 5: make an obituary presentation on what went wrong (hint: it's always management)
Unreal engine will probably do the same shit than Unity, Unreal engine might be opensource (not FOSS), I think there's the same clauses about production royalties.
I think Godot will not win simply because Unreal is so much better for 3D games what most comercial games use. I think Godot will become the indie favourite for 2D. Where it goes from there I'm not sure. Is the revenue sharing not enough to carry the game engine? Unreal/Epic is a special case. But is Unity mismanaged so hard? It still has huge market share.