We tried this in mid August (without even knowing that it was under discussion): TPE-HKG-JFK-MCO, fine from Taipei to JFK on CX but the CX agents in Taipei couldn't tag our bags for Orlando, just to JFK, which means that the people at the transfer desk at Terminal 7 in JFK wouldn't accept them and we had to take them on the Skytrain to the JetBlue terminal. Not a big deal as we had plenty of time and checkin there was painless but the interlining didn't seem to be a reality in mid-August.