This won't be very well explained, but in a discussion with someone earlier today, we kind of discussed the 50s idyllic, trapped in time nature that Fawcett City had at one point (or so we recalled). I'd suggested that it would be very viable to reuse that concept in a more sinister way, having Fawcett City be a city that just "disappeared" one day, only to return every so often with it's people unaging, unchanged, still in that 50s sensibility. It'd be sort of like the Twilight Zone, with an eerie maybe Stepford Smilers, Children of the Corn sort of vibe, and would serve as a reoccurring enemy to the Marvel/Shazam family, both through residents and maybe some of the D-list Fawcett characters that came over when DC bought them, given a boost of sorts.
Thoughts?