I believe they will. They are pretty close already. I know that the JPEGS coming off my new NEX are much nicer than anything that came off my D300. I think that the big question is going to be whether not mirrorless is going to replace DSLR's once the tech catches up.
The D5100 seems like a nice camera. Friend of mine has one and she gets some really nice shots off it. The size of the NEX is great. I have biggish hands and even so, it fits nice. It's super light and just has a good form factor. Does take a little getting used to going from a huge DSLR to this tiny little "toy" camera.
Camera Pimp member #1