I liked the first season of Carter. It had a clear vision and mostly delivered, and it was a lot better than AoS. The second season was less spectacular, it felt like it was mostly following a checklist and having another go since the previous season was well received, but didn't have nothing to say.
I think the main issue with these series is that they never delivered in their promise of expanding on the cinematic universe. While it was clear that they couldn't have cameos by Robert Downey Jr, Chris Hemsworth or Scarlett Johansson, it was not like the movies couldn't include Chloe Bennet, Iain De Caestecker or Ming-Na Wen as background cameos during Winter Soldier or Age of Ultron (doesn't have to give them lines, just show them in some of the shoots where they include nameless agents). By the same token, Agent Carter was advertised as "the origins of SHIELD", which they never really address in both seasons. It has been reported that TV licences and movies have a rocky relationship in Marvel, so it is natural that Marvel and ABC are not interested in continuing. I expect AoS will continue just until they reach syndication.
The only exception could be The Inhumans, which has been an element of AoS for so long it necessarily should inform some elements of the movie (not to do it would be disingenuous)... but since the movie is not released, it is impossible to estimate how much (if anything) it will inform.