Well, I have to move with times because my GPU has burned out and the integrated one supports only DirectX 9.0a(text in LFS is messed up since 0.F update) and SM2.
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. New PC will come in 4 days, YAY!
But at the end it is all up to you what to support and what not. Maybe gathering info about users hardware via LFS would be useful for you to decide. And if you see that last users with SM2 cards have upgraded, then you could move on with calm mind and thought that none of your customers was screwed.
Anyway, at least the period when you had to buy new PC every 4 years to keep up is over.