This is of course not including the yearly Unity subscription, where Unity Pro costs $2,040 per seat (although they may have Enterprise pricing)
Absolutely ridiculous. Many Unity devs are saying they're switching engines on social media.
That's still pretty awful really. If I have a game that's halfway through development as a developer I am now disincentivized to finish it. They are changing the terms halfway through development.
January 1st isn't exactly a lot of warning.
This would be borderline acceptable if we'd been given 6 months warning not 1 and 1/2 months