That's not proof. On the very next page, Tsunade states that she is the only person to master the technique, and is therefore the only person allowed to break all three rules.
I have no doubt that Sakura, for some reason, has been holding out and has some incredible new technique that puts her on par with Naruto and Sasuke. Albeit an extremely tired Naruto who has now fought on every battlefront of the war, battled the previous Kage, fought seven of the eight other Jinchuriki, fought Obito, fought Madara, and had a mental battle with Kurama, but nonetheless, Sakura will finally get a major upgrade. I just don't think it is going to be the same technique that Tsunade has. It might be a variation, but just because she is standing next to Naruto and Sasuke, doesn't mean that she is going to fight on the front lines with them. She might immediately fall back into a supporting position to heal them as needed or to gather more chakra.
