The physical-CD hangup is bizarre. The download-and-burn alternative is so easy, and the commercial logic against distributing physical copies so inescapable, that it really defies understanding why anyone with an interest in a game would refuse to buy and play it for this reason.
7YW is even more niche
Yes - but if 7YW (or pre-Napoleonic early modern in general) is a niche, it is a very large one.
Computer wargame design and marketing is hard to measure - it hasn't been around long enough and lacks definition since it can bleed over into quasi-simulation strategy games, first-person shooters, etc.
Interest in simulation-gaming of military history, on the other hand, hasn't changed all that much since the advent of paper wargames in the 1960s, and in that case there is a sufficiently large data-set to draw conclusions. In North America, the league table is pretty consistent by titles published and volume of sales over half a century:
1. WWII
2. ACW
3. Napoleonic
4. 7YW & other 18th c. Horse and Musket
5. All other topics and periods.
(I'm guessing the European list would see Napoleonic and ACW swap places.)
So 7YW might only rate 4th place, but it is still one of the major segments of the market. Wargaming, whether paper, tabletop or electronic, has never been more than a boutique cottage industry, but it is a stable one - interest in military gaming has passed the test of time - and the conclusions are obvious: 1) make good, challenging, detailed games; 2) make good games from the top three categories to support the company financially; 3) of all the niche topics, 7YW is probably the most viable.