Would they hurt sales of the Flex HT? Yeah. But the Flex HT Bitstream would be just that... a Flex HT with some additional decoding capabilities. It wouldn't be an entirely new model. And how many would buy the Flex HT if it had that capability, but don't because it doesn't? I'd argue that that very much makes up for the loss in Flex HT sales. Besides, the cost of adding bitstream support is probably way less than they could charge more. Would I have paid 300+ for a Flex HT with bitstream support? Absolutely. Would it cost that much to add the functionality, even with licenses? I think so.
Anyway, what's the serial number on yours? Mine is 101*, so I wonder if they have sold 10+ units or 1010+ units at that point.
I doubt that Canton and Nubert have bigger sales volume. Their market is basically Germany. And then German customers who have active speakers by either Canton or Nubert, plus a few more. Whereas MiniDSP has the entire world, with a well known brand in this space (unlike Canton and Nubert, which are probably pretty much unheard of outside of Germany (well, at least Nubert, they don't sell outside Germany)). MiniDSP also have a unique product that scratches the itch of many audiophiles. You get good DSP processing and a high quality DAC at a very reasonable price (what else is there to buy? A Trinnov?).
IMHO a Flex HT with bitstream is something many are dreaming of. I mean how many have bought an AVR only to use it with an external amp or two? The Flex HT with bitstreaming would be the ideal device for that use case. However not having bitstream means people need to jump through a ton of hoops, get several additional devices to make up for the loss, perhaps buy a new TV, etc. And it adds a ton more clutter.
What MiniDSP has done is build a great passenger car but without seats. Some (very few) will be glad that they can add aftermarket seats or don't need any at all, some will begrudgingly add aftermarket seats or rather build their own, and most will just skip this model and go elsewhere.