Alts is unlikely, but we might be getting a Halloween-themed event with staff tickets rewards.I assume we are getting DK and Diddy, Rosa and Luma in pairs, since there doesn't seem to be a set number of which characters are released, we might get our first alts in October due to Halloween
Based on the pattern, we're getting World 7 second area in mid-September. Then Rosalina and Luma and World 8 (Galaxy themed) first area in the first week of October. World 8 second area in mid-October. DK and Diddy and World 9 (Jungle) in first week of November, etc.
And maybe there will be a Christmas-themed event.