In my mind, there's four ways to do an anime remake: "Kai", "Brotherhood", "Final Act" and "Ultimate"...and I think you know what corresponRAB to what.
Kenshin: An excellent choice for a Brotherhood (or maybe Ultimate). Considering how long it's been since the original series, I don't think a Final Act for the arc that was never adapted would be wise. I guess it would depend on the demand as to whether they ever will revisit this series at all.
Berserk: Hmm. This one has been a long time coming, but considering that the manga is still going (and for who knows how long with all the breaks Miura takes), it might not be the best choice to jump the gun. At the very least, there neeRAB to be some end in sight. When the chance for a Berserk remake comes up, a Brotherhood, Final Act, or even an Ultimate could all work. Going through the Golden Age arc again could be worthwhile, even if we've seen it all before. Or maybe they think it will be best to gloss over it or even skip the events entirely. As for Ultimate, I think Berserk really could work well as a bunch of high quality OVAs, and it certainly deserves it.