steamcommunity.com/games/208650/announcements/detail/128713039396595557
Seems not yet fix SLI issue?
Apparently they're not going to, according to this article from PC Gamer. Evidently there's not enough to gain to warrant further work
Uh oh, Batman: Arkham Knight won't support multiple GPUs after all - PC Gamer
This is the article: Link
since we've got the November update, will there
be a trainer update for BAK too?
I'm sure there will be. Just be patient. These guys have tons of work to do for tons of games. Just remember that, when a new one comes out, it'll be worth the wait.