There have been multiple attempts at making 240/4 globally useful. It pretty much just works on most gear today (except windows), but the resistance by the IPv6 crowd to opening up 1/16th of the ipv4 internet for general use, astounding. There have been multiple internet drafts that did not make it through the relevant committees. Example: https://www.ietf.org/id/draft-schoen-intarea-unicast-240-03....
This makes it sound as if the ipv6 crowd would be larger than "the windows crowd". Perhaps start with convincing every windows user first, then "the ipv6 crowd" should be easily convinced.
