I used to practice at a Vietnamese Tiantai Temple in Texas. I took refuge and precepts with the monk there and still try to live up to his example even though I hardly learned a small fraction of what he has to teach. Unfortunately, my teacher's view is that his Vietnamese lineage is rather rare. According to him, aside from his preceptor, he was not aware of anyone else in the lineage. A good friend of mine has been studying with him much longer than I was able to, but as a householder, he has limited means to keep the tradition going - unless they find people willing to ordain. I believe there are pockets of teachers keeping the tradition going aside from the Tendai tradition in Japan, which was alluded to in earlier posts in this thread.