Too early to tell, but it could signal the start of a trend where developers and game studios at least entertain the idea of having a look at other engine before going with unity.

Don’t underestimate the sunk cost of Unity. it’s big, it’s taught in game classes, you might have years of in-house tools which you couldn’t re-use.

I can see hobbyist switching and game studios with games that are easy to port, like arcade-style 2d games. For a lot of studio switching is a real risk of bankruptcy, more so than the extra fees. It will take more than a few days for Unity to fall, or even have an “exodus”.