The separation of the imagifier from the squad (ie. giving the faith buffing ability to a character who can use it on a nearby squad rather than keeping it within the squad itself as an upgrade) in Apocalypse does not mean they will do it in the dex. I think whichever decision they make, it will be very strongly dependent upon/ connected to the new faith system.
Releasing a set of Sisters data sheets in addition to the bulletin does take some of the sting out of how weak the bulletin turned out to be, because at least I feel like I got some content. And the Apocalypse Index does imply that we will be getting a faction focus article; this too will be in addition to the bulletin. Either way, it's almost guaranteed to address acts of faith for Apocalypse- even if it just presents 2 or 3 examples of assets which represent acts of faith.
I'm hoping we get the Blackstone expansion with the new crusader or a sisters kill team in August and or September as a teaser for the big release, but it would be hard to do without revealing how acts of faith work. Maybe they'll release the AoF system as a bulletin in order to allow them the option of pre-dex kill team or blackstone. These teaser would sell, in part because of sisters hype, but once the dex and the new range drops, people will buy the 40k releases instead.
I just bought Blackstone, and while I love the game, I did it because I wanted Taddeus and Pious. If there had been plastic sister models available, that never would have happened.