Don't worry about the talking - I'm 28 and my parents are still talking to the wall!
-as long as he responds to 'direct authoratative questioning' he should still keep his vocal acuiety working (and working in a school system). ie your going to have to be authoritative now, not later.
-I think what helped me 'get out' while growing up, was the way my dad pretended he had an answer to everything..... be the technical dad, make out as if you are a walking dictionary.... (Hopefully your son is young enough for you to take on that role), I asked my dad everything, but never spoke to either one of my parents... all I wanted was an answer! ... my mum has had to pay for it, by raising a son that can't string two sentences together for her to listen too or reply too. ---It maybe advisable for both parents to become the repository.
-The offshoot for the parent being the repository, and the evident fast evolution in information and education is, that by the time your son ends up being smarter than you, conversations/being the library, will be nullified ... unless your not only a repository for general information but one on a specific topic... eg. turn a favorite topic of yours into his favorite topic (takes time, and he also has to be interested) eg. politics (should always stay the same ie don't pick something like technology, he may become apathetic towards your knowledge -thinking he knows more)
With me it was technology/invention/general science ,, and politics/history - I only talk the later today (I surpassed dad when he buaght me a PC) , on the odd occasion he still buys a Popular Science magazine, which I understand to be him, trying to invigorate the 'old times' , I usually skim over the mag and piont out to him pionts of interest.