I’ve implemented the same idea and published it as a package so it can be installed directly from within Sublime with Package Control:
Press ctrl+shift+p (Windows, Linux) or cmd+shift+p (OS X) to open the Command Pallete. Start typing ‘install’ to select ‘Package Control: Install Package’, then search for AllAutocomplete and select it.
Code is here: https://github.com/alienhard/SublimeAllAutocomplete