I should clarify that I don't believe they would specifically dress any Disney character as a Marvel or Star Wars character. But I would not be surprised to see some sort of additional challenge medal tied to the two race weekends where it's possible to earn Coast to Coast in 8 days. For years, those who ran the 5K and the Goofy called that the Dopey before runDisney formalized the Dopey. I wouldn't rule out some sort of Grumpy Challenge tied to marathon weekend (5K, 10K, Half) or even a 5K,10K, Half challenge tied to the other race weekends.
Based on the recent medal changes runDisney has made I think we're seeing a shift to unique medals each year instead of the slight variations every year. There are only so many ways a regular runDisney participant can display those medals. And it can get, well, boring if they always receive essentially the same one. This year alone, Princess, Disneyland Half, Dark Side, and Tinker Bell all received new medals that are very different from the previous years design with no anniversary race. And in the case of the older races, the new medals are substantially different from the medal they've used for years.
As people have begun to complain about the same medal every year, we see new medals. Disneyland Half may well be going with a different theme each year. When I first started, there was only one challenge event for one race weekend and that was Goofy. Since then they've added an official multi race challenge to every race weekend and have introduced two new Coast to Coast challenges tied to specific race weekends and the Castle to Chateau.