I think LISP will be around for a long time to come. It is simple to learn, compared to many other options, it works well and maintains compatibility between releases. You can still use LISP on the Mac as well, although some functions do not work (yet, I think they will add more as time goes on). It makes AutoCAD far more useful and more importantly easier to market, which to AutoDesk means $$$.
So, really, it makes sense to me that they will keep it for a long time.