No pub is based on HTML and is viewable on different devices which must look different. So will not meet that requirement. I think annotations also are not par

No pub is based on HTML and is viewable on different devices which must look different. So will not meet that requirement. I think annotations also are not part of ePub they need to be part of a specification that build on epub. epub is the original. Long term preservation is there as long as you don't try to do complex formatting in CSS.