One of the things I loved about Rogue One was the dimensionality it brought to the Rebellion. As much as I always rooted for them in the past, the Rebels were pretty uniform and so squeaky clean and wholesome as to be a bit boring. We saw a group of desperate people who disagreed, with different ethics and thresholds of courage or risk. And in Cassian we had an avatar of that complexity. What would you do for a cause that is so important? How much do you sacrifice? That is rich ground for stories. I think this show has great potential and am very excited to know we have a Rebellion era show coming (my favourite era for SW story telling).
I'm hoping we have K-2SO in the show as well. Alan Tudyk's name was notable for its absence in that press release.