Basically yes, that's exactly how it works. Devs create a new Anti-Cheat system that works for some times. Then some Hacker/Cracker/Cheater finds a leak into the system and allows cheats to come back for some times. Then Devs fix the leak and cheats are under control again. Then a new Cheat-System comes out e bam, the cycle starts again. For what I can say by my personal experience in On-line games, that's how it worked.