One of the reasons why I like this idea of including Nova, and why I started this thread, was because of where they could go with Nova, especially a Richard Rider.
As someone else mentioned, since we already have the Nova Corps, it seems like a perfect time to introduce Nova in a way that makes a lot of sense.
We have Rhommen Dey, who could easily be used to give the power to Rider, per canon.
They obviously want to expand the Marvel Movie-verse, and introducing Nova would do this and could lead to other things.
But most importantly, it seems logical that in this next movie something big is going to happen to NOVA. Yes, maybe that will end up being in the third movie instead, but in a lot of ways, in order to make the story compelling, showing NOVA getting utterly destroyed would be huge. Showing NOVA Prime dying and Rhomman Dey escaping with either a stone, or with the NOVA force, would make so much sense, and fits right in with the Nova story.
To me there really are two ways to give us Nova, as I've previously explained.
The first is to show the NOVA Corps, and NOVA Prime, defeated/destroyed and Rhommen Dey escapes with the stone or the force. Maybe that's all we would see until an after credits scene, where Rhommen would find his way to Earth and meet Richard Rider (hopefully - NO ONE wants Sam). This could lead to Nova in the next movie, or his own flick.
The second is to establish the above as part of the GOTG movie. Have Nova be part of the movie and have him travel to Xandar, fight with the Guardians, and ultimately give up his power to help reestablish the Corps. Then, in either another movie, or better yet, a mid or after credits scene, show Night Thrasher "helping" Richard Rider to once again become Nova. This would, of course, lead to the New Warriors as either a movie, or better yet, a tv series (that could cross-over with Agents of Shield).
New Warriors could be an amazing commodity. There are some compelling characters and stories, and it would appeal to a slightly younger generation than Agents does. Not saying that the New Warriors needs to end up getting caught up in the whole Infinity War, but as an expanded universe team doing their own thing, it could be very appealing!