Having seen the extended Comic Con footage it does not look like a rehash of the series. They might have to explain who the Bradleys are, but everything else felt very straight forward.
I am incredibly bias because Sam Wilson is one of the hills I will die on, but the footage looked excellent. I was really surprised how much subtle changes in what they showed enhanced my hype. They are holding back two major plot points.
I do agree with some others that Bucky should have been in this (and I say that as someone who never wants to see Bucky again). But Spellman had his own agenda, so whatever. That said, I am excited for the end credit of Thunderbolts to just be Sam and Bucky like: “Where the fuck were YOU?” “Me? Where the fuck were YOU?”