The follow mode looks really nifty. If you want some ideas for useful features:
-Move forward and jump over obstacles without following Mario.
-Change message/teleport Mario/stop following when a certain screen is reached.
-Wander around until talked to, then follow Mario/move forward.
Things like that would make them very useful to add "quests" to levels, and would make it possible for to use the same sprite rather than change levels when you need to NPC to act differently. It is really impressive that you'll be able to do so much with one sprite, I hope that with so many features it doesn't get complex to use. Include a guide when you release the sprite for those of us who don't know their way around a .asm or .cfg