Isn't asking a group of architecture students if they foresee a future for religious architecture kind of like asking a group of cattle ranchers if they foresee a future for carnivorism? What do you expect them to say?

I take the "spiritual but not religious" thing with a grain of salt. Many who call themselves that are no doubt sincere seekers who reject organized religion. But I'm pretty sure there's also a sizable number who check that box because it sounds better than admitting they lack a metaphysical imagination and like to sleep in on Sundays. 

As for religious architecture in the future, like in the early Christian era I expect form to follow function. Living rooms will suffice nicely for the "where two or three are gathered" kind of small faith communities likely to emerge in the years to come.