Announcement posters went up this week in all buses and Metro stations announcing "Le coupon de la Carte Orange disparaît bientôt !". (Imagine a picture of the carte orange ticket with a big red X across it in the middle of the poster). The posters are announcing the last days of the CO "coupon" ticket and the shift to the Carte Orange Découverte electronic transit pass. KDK has already covered this in previous posts but basically, from now on, you'll need to pay a one-time fee of 5€ and provide an identity picture to get a Carte Orange Découverte card, and then you "charge it up" on kiosks or at any ticket window in the Metro system. Initially, it's a bit more trouble to buy the card but recharging is easy and usually doesn't involve standing in lines. All the same rules as the coupon version still apply (week begins on Monday morning, ends on Sunday night, etc).
The new system is fully operational now so you should expect it to be in force from here on out.