There are some instances where you can get similar treatment.
Delta, for one, offers flights from ATL to LAX and back on both their 767 and 777 aircraft that are continuing on to international destinations. I've been on the DL 777 from ATL-LAX that was continuing on to either Tokyo or Beijing (after I got off in LAX), and it was their premium product. I had a similar ride on the return flight on a 767 that was continuing on to Buenos Aires (after I got off in ATL). So, there are a few flights out there but not many.
BA does (or used to) stop in Detroit on the way to Houston, but as others have posted, you can't buy a seat on the intra-US legs. Too bad, a tier point run would have been nice.
You may also get lucky in the airline is positioning one of those international birds for a particular reason.