Shukfir
Auto-translated
I don't know what it could be, but there's one idea: they'll bring back Railag and tell his story after his disappearance in Hammers of Fate.
No. Erwan Le Breton has hinted several times that they will continue to delve into the past. The next "stop" will be the era of Shantiri. Although it is quite possible that in H7 they will not yet jump to it, but will continue to describe the events of the middle of the millennium: the Underworld War, the War of the Broken Staff, the Third and Fourth Eclipses...
And regarding the era after Dark Messiah, according to Le Breton, they might only write a book about it.