there's space for a variety of mobile devices. today's ultrabook is just fitting a "premium netbook" niche, which is fine - it's a valuable use-case. it's not the same use-case as tablets, though: they're are more of an appliance, less general-purpose, not suitable for serious typing, more for reading, less for multitasking. that's not to say that touch wouldn't be welcome on ultrabooks (actually, the big improvement there would be higher-quality IPS-type panels.)
Making products thinner and lighter is the path most developments take and this is what is happening in mobild computing too. I would see it as a next step in laptops but hope they don't mimic the tablets because that would mean taking aways the high computing power a laptop meant as a portable computing device.