Maybe they could add in the game where is not just one long chain of levels, maybe they could put in where you could go one way or the other. Make your own path through the game then have them start to chain back together around the end level or so. It would add more replay value to the game, plus be a fun idea to try.
It would be cool if its just one big world and you travel around defeating bosses Dark Souls style or even Rogue Warrior style, everything in a few lives. :O dynamic world generation! Totally possible with this game as all closed off sections are basically chunks.
That would be neat, like have there be a hub witch the play could go back too. And they have to get different items from each level ^-^