One thing slightly perplexes me about the choice of Eberron (other than always wanting to type it Ebberon, IDK why I do that).
Eberron is a 'kitchen sink' kind of setting, it carefully made a place for /everything/ in D&D lore at the point it came out. 5e may be trying to appeal to fans of all editions, but it's not the kind of all-inclusive bloatware that cries out for a setting like Eberron (nor FR, nor Planescape, for that matter). A setting, like Dark Sun, that might introduce some new stuff that'd mostly just stay in Athas, would've made more sense. Same with Dragonlance. 5e's measured pace of output has kept it light/shallow on the kinds of options & universal lore that settings like FR/Eberron/Planescape (and I'm guessing Ravnica) are lousy with. The 5e design/publication philosophy and AL policy of Core+1 lend themselves much more to a series of settings that wouldn't be all-encompassing or cross-pollenate much, but be neatly self-contained in one supplement.
Maybe, they're actually going to hire another designer or few, and that pace of publication is going to pick up?