Just stumbled across this leak but so far, no other information exists except for this teaser of a splash page and a possible leaked photo from an event upcoming in Japan: https://campfireaudio.com/solaris/.
Sadly, we won't know more until they're officially announced on 10/26.
I'll be curious when more details come out but looking at the nozzle (similar to Atlas/Comet) and the size/shape of the new housing, I'm willing to bet they'll use the new 10mm ADLC dynamic driver with several BA's for a TOTL hybrid. With the Dorado being discontinued, and the Polaris (a hybrid) hanging out in the mid-fi camp, that seems to be the most plausible outcome. There is a chance they could be a new multi-BA IEM to replace the Andromeda but I doubt that considering the Andromeda S just launched.
Note: Image from Reddit, take with a grain of salt.