Ehm... man I dunno if you noticed but Dante had someone to fight against in every game...
I'm saying what if Rebellion gets stronger because every game Dante has a legitimate cause to fight against. Like Mundus in DMC1, Arius attempting to use demonic power to rule the Earth, or opposing Vergil's disregard for humanity in DMC3.I think he meant someone who could rival dante now or even be stronger , and rebellions power is a manifestation of dante's , so the more powerful he becomes the more powerful it does