I too would hope for something more in line with 1e or 2e WFRP. I really enjoy the system.
I'm pretty certain they wouldn't use FFG's system that was used in 3e, as I think that's specific and OWNED by FFG (or Asmodee now).
I personally don't mind if they use AoS, though I imagine if they do something like that, they'll utilize an era type idea like was used in the SW RPGs by WotC where you can play in different eras of time. That way, they have their main focus as AoS, but allow anyone to play in other eras of Warhammer Fantasy Roleplaying.
However, I don't think I'd buy it if they require special dice like FFG did. Even going a 5e route would be preferable to that as at least I already have dice that can be used for that without having to invest in these special dice which work for ONLY ONE system.
My preference though, as I stated at the top is that they go back to using a system more like the 1e and 2e type systems, than going with another system (like D&D) or creating a new one from scratch.