Taken from Michael Condrey's Twitter. He is one of the heads of Sledgehammer, so this is about as official as it's going to get for now. Unless Activision comes out later and says there is a Wii U version being handled by someone else.
https://twitter.com/MichaelCondrey/statuses/502094586865405952
Thanks to CharlieIntel: http://www.charlieintel.com/2014/08...advanced-warfare-wont-be-coming-to-the-wii-u/
EDIT:
EDIT 2: Confirmed by Activision to Eurogamer.
http://www.eurogamer.net/articles/2...re-dev-confirms-there-wont-be-a-wii-u-version
https://twitter.com/MichaelCondrey/statuses/502094586865405952
@MichaelCondrey call of duty advance warfer is goin to be on wii u ??
@1422644 no, no WiiU. That was an Activision decision. We are focused on XboxOne, PS4, and PC.
Thanks to CharlieIntel: http://www.charlieintel.com/2014/08...advanced-warfare-wont-be-coming-to-the-wii-u/
EDIT:
Treyarch is not working on it.
Another guy asked a follow-up question about High Moon. He hasn't answered that one yet.
EDIT 2: Confirmed by Activision to Eurogamer.
http://www.eurogamer.net/articles/2...re-dev-confirms-there-wont-be-a-wii-u-version