I've been burnt or nearly burnt with new tech over the decades and consider myself a bit of an early adopter.
4K and UHD are interesting ideas, but I'm really not interested in replacing my entire hardware investment (including the current HDMI cables in the walls) just for a better picture. (Though the improved colorspace is somewhat tantalizing.)
Also, I've just recently gotten comfortable buying bluray discs in any quantity since I know I can rip them to my home media server. What sort of advanced copyright protection are the newer formats going to have? How many years of having to rely on a dedicated player? (I've just detached my dvd player from my TVs and likely will detach the bluray players as well.)