The sky is not falling. This is an industrial product. There are TONS of Pittman 9434 motors for sale on popular auction sites. Lionel probably has many in stock, since they also used them for about eight years. Pittman's own website (Hayden Kerk Pittman) still shows specs for a 9234 motor which is electrically identical, except that it has wire leads instead of blade terminals for the brushes. Considering all the hard-to-obtain parts, a failed Pittman motor won't sideline an MTH loco 50 years from now. More likely it'll be worn out rubber tires 
As long as the worm gear isn't pressed onto the motor shaft (which was never the case with large Premier steam locos) you can buy a Pittman motor and install it yourself.
That brings me to the next point. With today's locos everything is integrated. I don't necessarily like this approach, but the motor, the gear ratio, and the electronics are (hopefully) optimized to work together. Some folks have alleged that Pittman motors are a bit fussy and don't play well with all types of electronic speed control. So if this isn't a crisis, it could be an opportunity.
All that being said, your point is valid. The manufacturers should list (1) the type of motor being used, (2) the gear ratio, and (3) whether the gears are self-locking or back-drivable. If you look at a Lobaugh, Max Gray, or US Hobbies catalog from the '40s, '50s, and '60s, all of these specifications were clearly stated. And with those locos, if you didn't like the stock setup you could obtain a different gearbox from the manufacturer and install it yourself. We're not so lucky! So what are they hiding? What are they ashamed of?? My wallet wants to know!
