The Coming Bloodbath

I work at a top NYC firm. I am paid very well and the quality of work I get is outstanding. My problem is there is not enough of it! My department has had little work for the past 12 months (enough to keep things "ticking over" but little enough that it is seriously boring).

I am concerned that my skills are not developing and, as I become more senior, I will not be equipped with the required skills. I have raised this with the partners who simply say that it has been a below average year but that, hopefully, something will come along by the end of the year.

Should I leave now before a bloodbath? Even if I survive that, ought not my professional development dictate that I move to another firm?