Coulson's resurrection is pretty moot at this point, since he's dead again. I doubt this LMD will be seen after this final season of AoS... both it, and Sarge last year, are because the team didn't expect to get renewed (and for two more seasons), they'd already decided Coulson was dying at the end of season 5, and they didn't want to finish the show without the guy (Clark Gregg, not Coulson) who held it all together.
I think all of the main characters could be worth keeping around in the MCU, either movies or TV or web shows. I'd like to see Daisy as a future Avenger or even X-Woman, FitzSimmons could fit in just about anywhere you need Science Guys. You could do a lot with Mack. And of course we need to see Robbie Reyes as Ghost Rider again at some point.
Any of these characters could be dropped in with no more than one or two lines of backstory, with more revealed along the way if necessary. Nobody needs to have watched 7 seasons of AoS to get any of them pretty quickly.