Well, considering how much stress Remtairy went through with juggling the Gym DLC and lapse of time....
Just imagine the amount of stress they would now have to deal with in making a new game that exceeds Karryn Prison? I doubt it is possible. Melty Quest was ok, but let's be honest. It doesn't hold a candle to KP.
A new game would be nice, but let us be realistic. I don't have any expectations of it being near what KP was unless they go a similar route of copy and paste.
And I won't go as far as some people claiming KP was the Greatest Hentai Game out there. It brought something different to the table and new compared to other hentai games(unless some people know of a similar approach in 'management,''battle-fuck,' and other elements before KP.) That is why you also see devs coming out copying KP ideas such as Love Space and Saria Reclaim. Not saying that is a bad thing either, I mean look at all the visual novels/eroges and then the sex stimulators, they had to start somewhere. That was the bar KP had set. So I honestly doubt the devs will create a similar bar on the scale of being good for originality and if they do somehow, well hats off to them.