They're gonna probably be exactly like the re-releases of 1 through 6 on the PSX were. There was an original and an arranged mode where the graphics were changed a little and the soundtrack was remixed. Don't worry, you'll be getting your originals. However, I've got the chance to hear a few of the remixes and to me they're more than welcome.
Oh yeah, and for Megaman 8, here's hoping they use the superior Saturn port for it instead of the PSX one.