The eFilm idea had a few things going wrong with it at the time.
Yes, the megapixel count was below what was really needed.
But mainly, the thing lacked the one feature that got everybody singing the praises of digital back then - the review screen on the back of the camera.
Digital cameras lumbered along in relative obscurity, until that screen came along - then everyone wanted one. The joy of knowing "it turned out", or knowing that you needed to delete that shot and try again was invaluable to the success of the digital point-and-shoot, or SLR.
The eFilm adapter didn't have that - never mind that a 1.3MP CMOS sensor at the time would have been pretty miserable.
Today, with much smaller circuitry, better battery life, and micro SD storage, I'll bet a good case could be made to create a digital back to go on an LX. But if you wanted to get the thing off the ground, you'd probably be better launching it first for the Canon AE-1 and Nikon FE.
I'm sure there's other technical challenges to overcome, but if they built digital backs to go on a Hasselblad 500cm, I'm sure 35mm bodies are possible.
Still, if someone pulled it off, it would probably three seconds before the whiners at dPreview were asking "why doesn't it shoot 4k video?"