After Heroes Call, my guess is that they will concentrate on getting a proper campaign out. That will probably take up much of the rest of the release schedule for this year, unless they are planning on releasing it, much too slowly. I am hoping that they will expand on the power struggle in Ubersreik as outlined in Lure Of Power. That looks fascinating!
The problem with a campaign is that normally only 1 person in the group buys it (the GM), I'm not sure they'd want their enitre release schedule for a year to only be bought by 1 person in each group. Having siad that most of the expansions so far are probably only being bought by the GM in each group anyway?
It would be interestig to know if players have bought the signs of faith expansion for example, because they are playing a priest, or if the majority of buys in the group have been by the GM (dice, player's guide etc being theobvious exception).
The other problem with a campaign is that not every GM buys it, as they are playing homebrews, or it doesn't fit in with where they are with the current published adventures etc, so I think FFG dedicating resource to a campaign could be a big risk.
Having said that, I guess a campaign that really becomes lengendary could help increase the sales of WFRP generally, but I still think it is a big risk.
I think FFG have more or less get it right so far in that in each adventure that they release, a major new adversary type or PC/NPC is provided, along with action cards so that even if the adventure itself isn't of total value to the playing group, the stuff that comes in the box is.
Personally, I think they'll continue in that vein for future products.