While I believe that Angry Birds hasn't topped Super Mario Bros. as a franchise, at the very least it has reached the same level as SMB relative to its age. Just like SMB, Angry Birds has a TV show, an upcoming film, toys, merch, etc. It's everything SMB had back in the day.
Now, the question on whether AB will be around for long (30+ years), it's anybody's call. Rovio can elect to change AB's gameplay (Super Angry Birds) to ensure its relevance. Remember Mario Bros started with a different gameplay.