I'm not interested in rotating formats in general, and nobody in my playgroup plays Brawl anyway, but I had this idea for a (purely casual) Brawl variant that I call Retro Brawl. The idea is that each player gets to pick any point in time from the history of Standard* (or the current Standard environment, for all I care) to determine what cards are legal in their respective deck. I'm pretty sure this would go horribly wrong as a competitive format, but it sounds like it could be fun at the kitchen table with a small handful of players who like to experiment with different sets and aren't trying to break the format.
I suggested the concept to my playgroup and they thought it sounded cool, but they didn't really know what to do with the idea because they felt they didn't have enough older cards from the same Standard environment to give them any interesting options. I kinda started building decks around
Rith, the Awakener and
Darigaaz, the Igniter (both for the Invasion block/7th Edition/Odyssey block era) to play against each other just for fun, but I didn't finish them due to a lack of time and motivation and because I ended up needing some of the cards for other decks... Maybe I'll give it another shot some time.
*A good overview can be found here:
https://en.wikipedia.org/wiki/Timeline_ ... d_(Type_II)