I have been told that is indeed the case. Those changes roll out to Seasons and Non-Seasons at the same time.
Season focus is using those changes and the Leaderboard changes. So, maybe season of solo play vs group play will be how we think of it.
Honestly, I am thrilled to see Solo having some major changes seeing as that is the mode I play and there have been tons of comments for years about how far behind solo play was.