I don't know how it is in North America, but it appears that most people that buy a new TV here in Holland are buying a Widescreen TV (We don't have HDTV in Europe).
I encode almost all my movies for 16:9 Anamorphic and every Widescreen television I've tried them on plays them well as Widescreen.
They look shit on normal TV's, but I like the extra lines. 352x288 at 16:9 looks just as good to my eyes as 352x576 at 4:3 letterboxed, maybe because my TV's zoom function to show 4:3 as 16:9 doesn't look that nice.
(I still prefer 352x288 because that plays on all the DVD-players of my friends and acquaintances)
One strange thing: A friend of mine has a six year old Philips TV that can actualy put a 16:9 anamorphic source within a 4:3 letterbox. He never knew what that function was good for until he started borowing some of my KVCD's. The picture even looks better, because he's using fewer lines of the TV to show the 352x288 picture