I don't want to incite the flamers here, but as someone who works in the product development & marketing world, I can tell you that companys tend to listen to their paying customers, not internet fanboys, and why they are smart enough to look at the competitive environment. That's the reason they left 4K resolution off of the C300 and why they aren't building a 30+ MP camera.
Fuji has brought medium format within striking distance of high-end DSLRs and while Canon has the resources to compete, why spend millions on R&D of a whole new system (i.e. with MF you couldn't use EOS lenses) to compete in a new space when you can (continue to) dominate the SLR space? Also, while the internet is full of people screaming for 30+ MP, 1080/60p, 4k, 20fps, etc. the majority of Canon's professional customers (who are actually buying their gear) clearly aren't using or needing those features yet. I'm sure they want them, too, but you'll notice that most professionals don't work with the latest bodies or lenses (unless they are Explorers of Light, etc.). They are more likely to stay with what works, see how the new stuff works out, and then buy as time & money allows. Canon has to reassure these pros that the new gear is not only advanced, but also reliable. If your income depends on your gear (unlike me and most posters on the web) a 40MP camera that breaks down is worthless and a pro would rather shoot a 10MP camera that works.
Just my two cents as a technology lover, but also a realist when it comes to products.