Just to say that the question might not only concern niche games. Any game that you do not buy shortly after its release might have a negative impact on the franchise (because most sales happen in a few weeks, with rare exceptions of course).
Great point. Completely agree this applies to any niche games or even any niche market as a whole.
My personal connection and the reason I posed this is me considering whether or not to pay full price for the fate/stay remaster as well as the tsukihime release.