They've since mentioned a few other reactions being available to anyone with the feat or other ability. Like how other classes can get AoOs and the shield thing seems to be untied to class, they just used paladin as an example there (There was another paladin reaction mentioned to get an attack on anyone who crits one of your allies). This info has been scattered around, I don't think they have a good chunk of reaction information available all in one place. My guess is that classes might /start/ with only one reaction option but can get more with feats, class abilities etc.
Edit: Oh, looks like this was an old post, for some reason my feed put it at the top and I didn't see that it was from two weeks ago. So you've likely seen this info anyway, in which case never-mind.