Banners have almost always been MCU, but the only MCU property with any promo material so far is Far From Home, and that premieres before con. Then again, they did put up generic Avengers Infinity War stuff last year before End Game was even announced, so maybe they'll just put up other MCU stuff to get hyped. There's a lot coming, just not a lot of promo stuff ready yet.
And for the buses, since it's been Game of Thrones for years and that's over, I'm guessing they'll do either His Dark Materials or Watchmen. It's possible they'll do Westworld, but that's also a ways out. So I'm not sure.