If Tibet can be independent, then so can Northumbria, Mercia, Wessex and Kent. No wonder that this cause is so popular among the Lib Dems, among whom the English equivalent has had a following, carried over from the old Liberal Party, since their inception.
The sheer scale of the population transfers that would be necessary to partition multiethnic China into a Tibetan homeland and a Han homeland (plus at least 54 others, presumably) are practically impossible to imagine. The whole thing would make the partition of India look like the resolution of a Parish Council boundary dispute.
Even the Dalai Lama is officially opposed to independence. He is also opposed to any boycott of the Beijing Olympics.