Since the blue guy is upgraded in 4.8, can we also expect a new skeleton and animations coming out?
Sorry for the delay in response. The 4.8.0 version of the Animation Starter Pack contains animations for the new mesh. The screenshots are out of date at the moment, but the content is updated. As far as other marketplace packs not created by Epic, those content creators will need to update their packs (and most are, I believe).
The ART toolset has also been updated for 4.8 to match the bind pose of the new character. You’ll need to reinstall the plugin though.