There was an ad from IM in one of the N scale magazines many months ago showing new paint schemes on their 4650 as "coming", illustrated with a picture of the early version, but I haven't heard anything about a new model since.
As for the newer prototypes, I saw a BN car, still in the original early 70s paint, go through Prichard, WV on the NS last spring. It looked a little ragged, but was still running.