Preconditions for changing a representative glyph?

In light of recent news about New York adopting a redesigned "handicapped"
symbol

http://www.disabilityscoop.com/2013/05/28/handicapped-symbol-facelift/18034/
http://www.cbc.ca/news/yourcommunity/2013/05/revamped-handicapped-icons-coming-to-new-york-city.html

and the new signs starting to appear in public places

https://www.google.com/search?q=new+york+handicapped+sign+redesign

I'd like to ask: what is supposed to be the trigger condition for the UTC
to consider changing the representative glyph of
U+267F WHEELCHAIR SYMBOL ♿

to the new design?

Thanks,
Leo
Received on Wed May 29 2013 - 10:42:47 CDT