I'm kind of surprised that no one seems to be combining an AI (Artificial Intelligence). Like one of the sex chatterbots, combined with an animated sex sim.
In other words, an animated sex sim character that can interact with the user, learn at least speech conversation tuned to the action (maybe even learn behaviors/positions in the future - with enough animation libraries to combine and enough compute cycles?).
Example of a sex AI chatterbot:
http://karigirl.com/