Well if that is the case it is either a) illegal. b) the developper/studios already agreed on a license that would allow unity to change term and licensing fee

Well if that is the case it is either a) illegal. b) the developper/studios already agreed on a license that would allow unity to change term and licensing fee on stuff made long ago and screw them whenever they want. If the answer is b, then I guess those involved should just slap themselves and swallow it instead of complaining.