Suggestions for future HTML standard

It would be very useful to be able to embed HTML just like any WAV or
MIDI file. I know it's already available for JavaScript as a js file but
I still wonder why not HTML? If I use a footer on every HTML page and I
want to edit it, I have to go to each HTML page and edit it one by one.
I should be able to just edit one file called footer.html. embed
src=footer.html, that simple. I'm sure it couldn't be all that tedious.

Thank You,

Jed Hunsaker
jiddy@bigfoot.com