I don't think it matters their old selling points matter anymore.
There are more new players than old now.
Based on the released demographics, 55% of DnD players wouldn't have been old enough to play during the 2nd Ed setting boom. And 70% would have been 15 or less in 2000 when 3rd Ed was released.
Any setting book they release has to appeal to that 70% of players who have no nostalgia rather than the sub-percentage of the the 30% who were old enough to remember 'n' love Spelljammer and Mystara.
They could do anything and if they market it right and make it cool enough, people will buy. They could turn Birthright and Hollow World into hit settings now.