Here's my list on why I think FH will be cancelled after only 2 seasons and 44 half-hour episodes.
1. Reruns air more on Disney XD then they actually do on Disney Channel.
2. They never show new episodes.
3. No merchandise has come out, despite it's great ratings.
4. The X-Mas special almost premiered with no promotion.
5. This might be a bad reason but: I feel that Disney Channel orders next seasons if the show has been getting good ratings, good reviews or bad ratings and bad reviews, or decent. For example, Phineas & Ferb Season 1 was 26, but it became a huge hit, Season 2 was 39 episodes, and those were decent and Season 3 will be 35 episodes. One of the lowest I've seen is when DC renewed Kick Buttowski, Season 1 was 20 episodes, Season 2 will be 26 episodes (Dear God don't cancel that perfection) and Season 1 of Fish Hooks was 21 episodes, Season 2 will be 22 episodes...if my theory is true then wow Disney, wow.