Firaxis can't even make a spiritual successor to SMAC. Beyond Earth was terrible and basicly just a civ5 skin made by 2 modders supported by the Firaxis art team AFAIK. The good things I remember from SMAC were the units you could design and the terrain having real elevation. It's one of those games that were great for its time, but I wouldnt wanna play it now.
If you take a look back at previous civ games, then Firaxis added or expanded features - rarely removed or replaced features.
Civ1: Basic game
Civ2: More techs and unit stacking, larger maps + the previous.
Civ3: Culture, resources, golden ages, larger maps and Unique civs/UU + the previous.
Civ4: 3D graphics, religion, civics replacing governments, smaller maps and great people + the previous
From now on, here be dragons:
Civ5: Hex tiles, 1UPT and city states, smaller maps + most of the previous
Civ6: Districts, workers replaced with builders, eureka railroaded gameplay, predictable agenda system reducing replayability, smaller maps + most of the previous from civ5
Train crash:
Civ7: Smallest maps so far, swap civs, eras and entirely new gameplay.
I think you can find good things in all the games, I just think the magic is somewhere in the civ4 area. I'd love a civ game that had the unit workshop from SMAC, but improved and expanded. I dont think civ7 is actually a civ game at all. They replaced everything and just made it smaller. What were they thinking?