Personally I really damn hope there is no fourth age or futurology of any kind in civ7, beyond some "five minutes in the future" techs of the third era lasting till AD 2050. The games are supposed to cover humanity's history, not science fiction, I am supportive of orthodoxy in this regard - they are clearly not built to facilitate gamechanging nature of sci fi technologies (Internet and "immaterial" reality, transhumanism, space exploration, extremely complex nature of modern economy etc). Most importantly, the games are built around a "cast" of historical civilizations, cities, people, military units, buildings, wonders, quotes etc - any tacked on sci fi era is going to feel generic and lame when standing directly next to that and being unable to continue this diversity, consisting of generic technological toys lacking any cultural background. Besides, civ games always struggle with the endgame problem and the new game is going to be entirely constructed to deal with it, so I assume its entire pacing and structure shall lead towards release of tension by the end of the third era - it's not trivial deal to then make the game 30% longer on top of that.
I also very much don't want the civ games to contain speculative wackiness, because for me it clashes with the tone of "okay we have some humor from time to time but most of the time kinda want to present dignified version of real history", so if we (mostly) don't have blatant myths, cartoonish depictions and wacky "artistic interpretations" of real history, then we shouldn't have wacky cartoonish sci fi either..