A nice review has appeared about this TWHS in Canada, but did anyone keep track what happened after it was supposed to be nominated in 2012?

The statements about a "hoped for" nomination in 2012 all go back as far as I can see to early 2010.
"The preliminary draft of the nomination will be ready for submission to the World Heritage Committee in February 2011. - See more at: http://www.ammsa.com/publications/alberta-sweetgrass/writing-stone-provincial-park-be -nominated-world-heritage-site#sthash.6Ip58oGn.dpuf"

And in http://www.tpr.alberta.ca/parks/consult/notifications/docs/wos-faq-march-2010.pdf
which shows that active consultations were taking place in April 2010........

THEN........
Something called the "Alberta Parks Act (Bill 29)" seems to have emerged during 2010. Among its provisions were changes to the protection arrangements for Parks in Alberta. There seem to be differing views as to whether these proposed changes were detrimental to Áísínai'pi.
This letter of Nov 2010 from the Canadian Parks and Wilderness Society suggests that "The proposed, sweeping changes to Alberta's parks legislation currently being debated in the Alberta Legislature directly affects:
 One World Heritage Site (WHS) – Dinosaur Provincial Park, and one on UNESCO's tentative list for WHS designation - Writing-on-Stone Provincial Park (Áísínai'pi)"
Not a very good situation to go into a UNESCO Nomination with!!! But whether this had any impact on the nomination - I can find no reference. The Bill appears to have been withdrawn at the end of 2010 with a promise in early 2011 from the Alberta Government to bring it back again
http://albertawilderness.ca/issues/wildlands/protected-areas/archive/2011-02-00-tempo rary-reprive-for-alberta-parks.-will-the-bill-29-battle-need-to-be-fought-again
I can find nothing more recent

Interestingly the Alberta Parks Web pages on this park make absolutely NO mention of any UNESCO WHS aspiration http://www.albertaparks.ca/writing-on-stone/information-facilities.aspx