It will absolutely have a negative impact on the number of subscribers, and therefore OF's bottom line. To what extent that impact will be, I don't know, but I'm guessing it will be significant.
Only the most technically illiterate didn't know how to download videos before DRM, which means that a vast majority were downloading videos. When those folks realize that they can no longer do so, I suspect most of them will abandon OF completely, like many (including myself) already have. The value proposition just isn't good enough anymore. I mean, it was bad before, but not being able to download videos for personal use? That's where most people will draw the line.
Maybe that loss of subscribers will be enough for OF to backtrack the DRM thing, but I don't see how they could. They're too invested now.
As for them 'winning' and killing off communities like this one... I don't see that ever happening. As long as it's still possible to leak content, in some shape or form, the pirate community will carry on as it always has - though the quantity and frequency of new content will surely decrease.