Currently, public sub counts are abbreviated in most but not all places across YouTube. In August, we’ll make this more consistent by always showing abbreviated sub counts publicly. Creators: You’ll still see your full sub count in Studio! Learn more → http://yt.be/help/abbrev-count …pic.twitter.com/pmaKk4EU4k
I'm assuming this is to stop live sub-count livestreams, but why not actually fix fact that subscribers don't get shown videos, but are still seen as an important gauge by YouTube to whether you can have a custom url, a community tab or make any money at all.