"A billion game sales isn't really unprecedented, just look at two of the most successful systems ever that failed to do it." :PA billion games for a hugely popular system isn't really unprecedented. Both Wii and DS sold close to a billion physical games... each.
IR Information : Sales Data - Dedicated Video Game Sales Units
www.nintendo.co.jp
It isn't unprecedented because the PS2 already did it (plus an extra 500+ mil) but it's still a huge milestone that no-one else has managed to accomplish and it's excluding indie games, F2P games, etc that've become more and more popular this gen.