Macro lenses are usually designed for outright optical performance, I think a PF design is unlikely since this is more of a concession for compactness and ease of handling.
But I'm sure we can expect AFS, G, IF, ED, VR, Nano, Fluorine coating, and maybe an E aperture. Hopefully it will have a good tripod mount since macros of this length can hardly be hand-held.
A while ago Thom Hogan hoped a replacement 200 micro would be f/2.8 to replace the 180/2.8 ED as well. I hope not, since it would be the worst of both worlds - for macro fast apertures are not usually needed, and it wouldn't be compact and affordable like the 180.