Agreed with Ryika. People are just too pessimistic and afraid that their old ways and modes of work will be violated by the new game. I quite welcome the changes, as they mark some challenge to overcome, new things to learn. I might need to finally pick up 3D modelling so I could provide some simple Unique Building models for new civilizations. If that fails, we'll just make them without new models, or just with some reskins for starters.
Of course the main bottleneck is going to be how easy it is to implement 3D models into the game. It wasn't a huge issue with unique improvements in Civ 5 and in the last few years they started popping all over the place in Civ 5 mods. There's hoping that's the case with Civ 6 as well.
I know that not everyone will be able to devote a lot of time to learn new things to mod a new game, but I think it's the cost that can - and should - be expected of a new title. We're expecting from modders / ourselves that we start making mods for Civ 6 as quickly and in such quantity (let alone quality) as for Civ 5 after two expansions and three or more years of experience.