There have been multiple times talks about a Baten Kaitos on DS, as early as 2004 actually with the game first appearing on Nintendo's plannings on their Japanese website. I couldn't find any news on this in our archives here, but this, from 2008, when Monolith hadn't completely abandoned the idea yet :
http://www.cubed3.com/news/10149/1/baten-kaitos-back-on-nintendo-ds.html
Or better yet, an HD Xenosaga trilogy! That series never came to Europe and could very well do so in the hands of Nintendo (and seeing as their relationship with Bandai Namco Games seems to be pretty good at the moment with them helping out with the development of the new Smash Bros games, this could happen, who knows?). I know, it's yet another remake and not anything original, but I'm sure there are plenty of players out there who never got the chance to play it before (there's me at least ). And seing as Monolith Soft is now with Nintendo, if there's a chance for the franchise to come back once again, better that it be on Wii U and in HD !! But then most Nintendo players won't have played any of the series before, so better re-release the previous games.