I don't know, the sleepers still don't have names, so I'm not sure if they will make changes. I think that if orders have been lacking swapping the baggage for a baggage RPO would help.
I don't want to say MP absolutely never owned a baggage car like the MTL one, but the vast majority of their fleet looked much closer to the Wheels of Time baggage car.
The MTL Baggage RPO is a pretty close match to MP's cars of that type and the Wheels of Time baggage cars in the Eagle scheme are hard to find and expensive when you do.
My main hope is that if the set sells well, MTL will then issue the coaches and a diner as single cars.