I have no reason to doubt that New game plus will find it's way to the game at some point. The only thing is that it could probably take a while. My reasoning:
1) The skill system is very flexible and allowing for NG+. You can only gain so much power, since you can only slot 12 skills. But finetuning your build (through having a lot of points and being able to pick high tier skills from multiple trees) can increase your power just a bit further! This is something you cannot do on your first playthrough. You can make good builds, sure, but you can't make a perfect one.
2) The cap is 70, and many weapons in game already are higher than most players can reach legitly. This wouldn't be done just for cheaters. It just wouldn't.
3) My view is that in the first game, your main struggles are the shortage of abilities for 90% of the game, and difficulty comes from learning the enemies and a restricted playstyle. i'm hoping in ng+, difficulty comes from enhanced AI (doubt it) and a LOT tougher enemies. This'll give you the skills to cope with 'm, but punish you severely.
4) Replaying the game with different choices is something that the makers would want you to do (I know I do). And NG+ would be a much more comfortable setting to do it in. You've worked hard for your stuff, why should you not be allowed to use it? I'm speaking for me personally that I don't have the time to replay this game over and over. I'm replaying it once again, for the different choices, because I screwed up on some of them (damn you, consequences! I didn't mean it when I said I loved yen, please come back, Triss!!). NG+ on deathmarch would sufficiently change the game for me to actually warrant a new playthrough.
5) CDRED is the most customer friendly company in gaming I know. I trust them.
6) I'd pay for it, and I know others would too.
Oh, I don't post here much, so I just want to say: RED, absolutely one of the finest games I ever played. Congrats, this game can earn Game of the year 3 years straight for all I care.