You may not have realised, but this could actually be quite close!
If you have seen the movie "UP" you may remember* that it features dogs with collars which allow the dogs to talk.
I was watching a compilation of dogs making weird noises (because why not?), and it was obvious that what a lot of these dogs were doing was trying to copy human noises.
Unfortunately they lack the right vocal equipment for this (some of them got pretty close though!). However it is clear that they understand quite a few different words so if they did have the physical ability to speak, it looks like their brain would be up to the task, even if they are just capable of single words like "walk", "food", "play" etc. so it seems to me like its the physical side of things that is preventing them.
However If we assume that we are looking at a leap forward in light weight wearable BCI Tech in the next few years (Openwater) Then it seems reasonable to me that we might soon be able to put a little woolly hat on a dog, which would give it the ability to speak human languages.
The complexity of it's speech will likely depend on the complexity of its thinking, but from a tech perspective translating a dog should be less complicated than translating a human, and we all know BCI to text/speech for humans will be a huge priority.
Am I overestimating dogs? or underestimating the complexity of this? What do you think?
EDIT: Also if you think this is feasible, what will be the impact (if any) of intelligent animals (dogs, cats, elephants, dolphins, whales, apes, pigs? etc.) being able to speak? would we eat less meat if pigs could actually say "stop eating us you dickheads!"
*you may have repressed all memory of the movie "UP" because the beginning is so depressing, If so, you made the right choice.