From the IGN article, the kind of design they're using with the short stages sounds like the sort of thing that could be made with a shorter dev time, but it also sounds a bit shallow.
I imagine it will be something like the NG: black mission mode, except some missions will have larger stages and more enemies. The keys to this will be multiple characters and difficulty levels and replay factor.
It makes me a bit less concerned about the dev time, but more more concerened about the actual game design.