I think, sadly, that E6 films must be on the way out. Almost all of their commercial applications have been replaced by digital. They were the preferred commercial medium for color work because of the speed of obtaining a positive image, and the fact that for reproduction, they are highly preferred over type C prints by the print industry.
It is tragic, IMO, because of how pliable these films are for a color medium. They can be pushed and pulled in a way that matches anything but extreme tweaking with black and white. No such luck with C-41 films.
On the plus side, I have had VERY good luck with VERY expired E6 films and chemicals, so when the time comes when E6 goes away, making a good stockpile should keep me set up for about a decade past that point.
I Love TLRs, Ektar is a C-41 film. You can do it in the same tank with any other C-41 film...as I have done twice so far, with fine results. The film itself is not my cup of tea, but I can see why some people would like it, and it does not need to be sent to Kodak.