The other way around would be less satisfying I think. Am not sure how much of a 'role' the DLC characters are gonna have. Compare them for example to the characters who made it in the Subspace Emmisarry in Brawl, and those who didn't. I want my King K.Rool reveal trailer, and King K.Rool Amiibu toy.
Also, Dixie would perhaps make a better DLC character due to the fact she's easier to create. K.Rool would take a lot of time if he'd had to be made from scratch I'd think. And I doubt they'd would work on such a time-invested character as K.Rool past release if he'd easily take as much work as Palutena, Rosalina and Mii Fighters. Which is why I expect DLC characters to be mostly 'left-over' characters, with a lot of data already in anyway say the likes of, Lucas, Squirtle, Ivysaur, Roy, Dr.Mario and Mewtwo if he doesn't make it innitially. Or characters that could be easily made semi-clones, as Dixie, Lucina, Impa, Black Shadow and others.
So yes, due to the bigger "impact" K.Rool would make than Dixie by being released earlier, I'd chose for him to be on the regular roster, and Dixie being DLC.
Everyone is like this almost
Even I am guilty of maining a lightweight :
. But I have a lot of heavy secondary characters, one very noticable is of course:
. But also:
. So K.Rool I will definitely use. But by the rate all these light weight newcomers pop up... We might soon have to call even
a heavy weight...