This had been a decades long desire.Perhaps not different enough to warrant a setting, but I'd love Dominaria to be released as one. The art of Dominaria has enough info to run it and there was a planeshift article, but I'd like to see a fully fleshed out campaign. You could have the main setting which is the current timeline (perhaps set before the recent phyrexian invasion) then a supplement with info on the brothers war, and the later ice age. It could even have stats for the weatherlight, the MtG equivalent of a spelljammer.
(definately before the phyrexian invasion)