It would seem the main change is the ability to link Crypto Ancienne in order to gain TLS 1.2 support. It will do native OS9 users no good however because it involves running the two simultaneously in order to use Crypto Ancienne as a TLS proxy. That cannot happen under OS9's cooperative multitasking. That makes it usable (for us) only in Classic.
The BIG news is that Cameron Kaiser is finally throwing in the towel as a one-man browser developer. He posted a long, detailed explanation on the 10-4 Dev blog explaining the reasons. He left out one, which is that there are only 24 hours in a day, he has a real job and he would really prefer to stay married to his wife. So 10-4-Fox is also EOL. There will be other discussion on that, I'm sure.