The 85 update is not truly needed unless you are a completist and believe 'the whole line needs to be refreshed', all the lenses need to look the same in a brochure, etc. (i.e. you are in Canon's marketing group or you are a lens collector.) The current 85mm F/1.8 is quite possibly the greatest bang for buck lens that Canon currently sells. It's a stellar lens for the dollar, even 15-20 years after its release: http://www.photozone.de/canon_eos_ff/419-canon_85_18_5d?start=1
I owned an 85/1.8 for several years, and although I liked it very much, I ultimately replaced it with the 100/2.8L IS macro. I used the 85/1.8 primarily for in-studio portraits, where I only used it wider than f/2.8 experimentally. I liked the quality of images from the 100 IS macro better.
Whether or not the 85/1.8 needs
an update is for us mere photographers a fairly subjective question. (For Canon, of course, it's a business revenue / profit issue.) FWIW, my minor irritation with the 85/1.8 was its slight CA in some instances, and my major gripe was its clip-on hood, which I found cumbersome to attach correctly; when I didn't get it on right, it would pop off easily.
If I were Canon updating the 85/1.8, I would bring its optics up to current non-L prime standards, add IS (dropping max aperture to f/2.0 would be a small price) and give it a bayonet hood.
I'm looking forward to the release of an updated Canon non-L 50mm with true ring USM, with or without IS.