What they "should" do, is Add more content to the Carnival.
Add mini Avatar fights, where you could actually do the fights solo. Make it so basically any spell that's learn-able in DF content, also has an instance in the Carnival.

Limited or not, i think this is a good idea. For the more casual players who don't have friends that can rely on to carry them through the DF battles.

Going forward, some Blu exclusive gear from Carnival would be a good idea.

Tomes for spells from Carnival would also be could also work. Call them Blue Tomes, get a set amount from each stage weekly that you could "buy" the 4 and 5* spells with.

And a level 130 weapon isn't out of the question. Even with M&M5 its solo content, you don't need to compare it to other jobs.