I’d some plans to write my own e-pub reader, since all the existing ones are shite in their own way, but since e-pub files are secretly xhtml and css in disguise, it’s actually a hell of a job, much bigger than I’d anticipated.
I don’t think making network requests for files nor parsing any of those formats is so difficult, and while the actual layout rules interact in a complicated way they’re not insurmountable. However, doing it securely and in a way that runs at an acceptable speed is much harder. Tokenizing JS and interpreting it isn’t so bad, but that’s not going to run a modern website with tens of thousands of lines of scripts. Displaying video with hardware acceleration? Best bust out some code.
Moving to another protocol will either need the cooperation of everyone everywhere all at once, or since that’ll never happen, alternatively convincing all the major browser manufacturers to support both for a while so that other companies can enter the market, which will also never happen. Going to be a tough sell.
That is a thing of beauty. Bring the gravy boat to the table so that you can top it up to the brim, heaven.