Hi Melanie!  As the runDisney team evaluated the needs and demands for races, they decided to not bring back the relays this year.  They will re-evaluate before planning every event to see what best fulfills the desires of the runners.  There are currently no relays planned for the next set of races, but things are always being evaluated and examined. 
If you are looking for a race that is less than a half marathon, there is a new race this year called the Twilight Zone Tower of Terror Ten-Miler.  It is a night race, like the Wine and Dine, and will have a really fun after party at Disney's Hollywood Studios.  And of course, every race weekend offers a fun and festive 5K.
Please let me know if you have any questions about selecting a race!