One of the biggest pet collecting in-game holidays is coming up, Children's Week. It will start at the end of April and last for one week. As far as I can tell, no new pets have been or will be added as rewards for this year's quests.
Something NEW does seem to have been sneaked in, though, so don't pass up on this year's event (just in case!). Magical Pet Biscuit. Yes, these are back and Wowhead has them listed as one of the possible rewards for the Children's Week quests as of patch 4.2.0.
These biscuits are the same as Papa Hummel's Old-Fashioned Pet Biscuit, except you don't need a TCG code to redeem them (and they don't cost anything extra). They first showed up as rewards for the 125 and 150 pet collecting achievements, but were replaced by the two pets that are now awarded upon reaching these two milestones. Then the pet biscuits kind of just disappeared for a while.
We'll have to wait and see if they will actually be a choice for this year's Children's Week, but I'm hoping they will be. With three possible quest chains to complete, and each offering a bundle of 25 biscuits per quest, players who don't have access to TCG loot should be able to pick up a total of 75 (IF they don't choose any of the other rewards from the quests). These are pretty fun items and while 75 may seem like a lot, I think most collectors can burn through them pretty quickly. XD