Flash and Silverlight based ads will become extinct by 2013
Not so long ago,
Nonetheless, when Steve Jobs mentioned that Apple (iOS) will never support Flash in their mobile devices, Flash community was shocked. Second shock came from Microsoft which mentioned that version 5 of Silverlight could be the final release of Silverlight. (http://www.theverge.com/2011/12/10/2625339/microsoft-silverlight-5-released-will-it-be-the-final-version)
As all of us know, the problem of both Flash and Silverlight is compatibility. Flash does not work on iOS, Silverlight does not support multiple versions of multiple browsers and future browser support is in doubt.
Compatibility, which is being able to serve as much device/user as possible, is a key element in advertisement. Have you seen any billboard which cannot be seen from 2011 Porsche 911 but can be seen from a 2011 Cadillac Escalade? (we assume Porsche driver is following the rules and drives around the speed limit :)
The bad: Legacy applications written with Flash and Silverlight need to be rewritten in the near future.
Welcome 2012 and HTML5 !