It won't be an actual dough, it's going to be ... well, I don't know what exactly. I just don't see this retaining the properties of dough.
Why wouldn't it? I've used a cookie press for years. The dough that comes out of it acts like any other sugar cookie dough, and the cookies are much better than anything that comes in a plastic package. Dough in general is very amenable to be smushed, smashed, mushed, and extruded. Every kind of noodle made is extruded, after all.
You didn't read the parent post very closely, either, or you would have noticed that chefs use a TON of machinery. Chefs have been using machines to make stuff for a couple of hundred years. Other posters have already pointed out that there are specialty ravioli-making machines, for both large and small scales. "3D printing" for food is more like "robot that assembles food" than it is like plastic 3D printing, and that's a very reasonable progression of a very long term trend.
If you've ever watched one of those TV shows about catering, you would have a better idea of the possibilities. There are all kinds of things that a chef would be happy to assign to a robot, rather than a junior staff member, were a robot available. The OPs example of petit fours is one of many.
Remember all those stories about robots taking low skill labor jobs? Remember Humans Need Not Apply? This is that process in action.
Assuming, as other people have pointed out, that its programming interface is within the grasp of your typical chef and that loading and cleaning it is no harder than loading and cleaning a stand mixer. It will be a while before they reach that stage.