Here are two features that I think would be extremely helpful. Note the end goal would be to produce a single video file that you can overlay subtitles on top as another video file. ie: you want to make a video file with a subtitle track permanently on.
1) Export the subtitles, on their own, to a single video file, such that you can then add this file as an overlay video track in Premiere, and export the whole thing into what ever format you like.
2) Have Encore export the project as a single hi-def video file, with a subtitle track permanently on. (not as a video dvd or flash dvd folder)