A suffusion of yellow
Kaladesh would be interesting - mages replaced by artificers as mages are rare and largely outlawed. I can easily see Spelljammer being used as a link to the MTG settings especially if the Weatherlight is presented as a PlanesjammerI think one of the MtG settings is a Magitech Steampunk India, so there could be that.
I also think they'll do away with Crystal Spheres and the Phlogiston, as not too many people seem to be attached to the ideas of Ptolemaic Astronomy.
Personally I think the Ravenloft approach is a good one for Spelljammer and I’d want to see rules for Spelljammer design and Use, a Rock of Braal adventure and then a guide on world/sphere design