I use my Xoom mainly for couch surfing, and even when traveling, just as Marco just said, I use my smartphone to tether it, so I just can't understand why would I want an additional bill to pay.
Anyways, I think that eventually stuff like Motorola lapdock, Asus Transformer and Asus Padphone will be the norm, a single device to power different form factors, so the line between smartphone, portable PC and tablet will blur (no pun intended) more and more with each generation, already smartphones and and laptops are converging in features (ultrabooks).