Honestly, the thing I want from an official port that hasn't been delivered yet and probably never will be is a release from NICALiS of Cave Story that is as polished and thoroughly debugged as the original Cave Story itself. Whenever I just want to play Cave Story for the sake of playing Cave Story, I play the original. Why? Not just because of the AGTP translation, but another thing. Just by playing the original Cave Story, I can tell that Pixel took his sweet little time in perfecting every detail, and fixing every last bug he found. Since he was able to release the original on his own watch, there were no deadlines. He could simply keep debugging it and not release it until everything was perfect. Unlike commercial games that have bugs that the developers most likely are aware of, but didn't have time to fix due to deadlines. Now I can really sympathize that, actually. Not just because I understand the train of thought, but because I've experienced something very much like that myself. I once made a game in Game Maker, and due setting a deadline for it, I kept having to cut more and more corners, and leave a TON of bugs in it. And really, the end product was pretty ugly for anyone outside the targeted audience. However, honestly. NICALiS' releases of Cave Story are far more buggy than any commercial game I've ever played aside from Big Rigs Over the road racing. I have a bit of a prejudice toward NICALiS due to all of their releases that are significantly more buggy than the original Cave Story. Now I'm not saying that the original was absolutely completely beyond a shadow of doubt perfect and without even one single tiny little glitch, but it was very, very close to that. All their releases (even Cave Story+) are so buggy, that it would really be worth pushing the release date. Some like the Wiiware version were so bad that it got patched, but even after that, it wasn't really perfect. And don't even say that this is just because NICALiS is a small company. Rayman Origins was developed by a relatively small team unless I am much mistaken. It was originally going to come out December 2010. However, its release date was pushed to November 2011 (admittedly not to further polish it, but rather scrapping the idea of releasing the game episodically). And I've got to say, the final product is one of the most polished games I have ever played.
TL;DR
What I want to see in later ports of Cave Story is for it to be thoroughly debugged to the point where it does the original Cave Story justice, unlike all of NICALiS' other releases.