Having both in the inventory is not holding anything back, it's just good sold business management. Sell whatever is demanded, don't eliminate it from your business plan, when it's already in your engineering and sales inventory.
Dave, I have a 1999 GMC Yukon, it's a great truck, served me well over the years, I still have it and runs awesome. I've told the local dealer that if they could still sell trucks exactly like mine, I buy a brand new every year. He just laughs, and says we wouldn't be in business to sell you one every year. It becomes a matter of product evolution. If you keep selling the same thing over and over again it becomes who you are. MTH wants to be known for DCS being an evolutionary train operating system that can adapt with changing & trending technology.
From a production stand point the DCS remote is expensive to maintain, and the software is difficult to upgrade. The remote itself is limited by the buttons on it which hinders it's ability to add usable new features (Quillable Whistle). The cost MTH has to keep the app available is $100 per year (annual apple developer fee), to maintain the DCS remote would cost considerably more. Maybe smart phones and app will fade away but they will be replaced with something ever newer and MTH will again have to evolve with the demand.
Maintaining inventory is expensive. Software costs less than hardware.
Now when it finally becomes obsolete that is a different matter. Parts should be available for at least 10 years however. O Gauge trains are not throw away technology like the phones in young and old peoples pockets. O Gauge Trains are engineered to be passed down thru the family for generations. At least they were!
If MTH has it's way, DCS will never become obsolete. Weather it run by a HHRC, and App, Voice Command or by blinking your eyes, DCS is here to stay. I have PS2 engines from 2000 that still work with DCS technology that cam out last year (DCS Explorer). I'd say any DCS engine can be passed down, and our great grandchildren can run them with whatever control method has replaced the app without having to hope that a 60 year HHRC still works.
My nearly 20 year old truck isn't obsolete and never will be, in fact parts are plentiful for it if & when I need them. But why won't they keep making that exact same reliable truck model? Mine has 358,000 miles and keeps on rolling, with a track record like that it makes sense to keep producing it right? Yet they don't. I think they know something that we don't....
Out with old and in with new is happening everywhere and in every industry, you may not like it, but it is driven by public demand.