Well theoretically each Zen core can perform four times as many single-precision floating-point operations per clock as a Jaguar core. In actual use the performance difference isn't quite that extreme, but it's still large. And the Zen cores in a next gen console would likely be clocked faster than the Jaguar cores in Xbox One X.
Lets compare theoretical single-precision floating-point operations per second of CPUs (not GPUs)
Xbox || 2.9 GFLOPS
PlayStation 2 || 6.2 GFLOPS
Nintendo Switch || 65.3 GFLOPS
Xbox 360 || 76.8 GFLOPS
PlayStation 4 || 102.4 GFLOPS
Xbox One || 112.0 GFLOPS
PlayStation 4 Pro || 136.3 GFLOPS
Xbox One X || 147.2 GFLOPS
PlayStation 3 || 204.8 GFLOPS
Zhongshan Subor Z || 384.0 GFLOPS
Hypothetical Next Gen 8 core Zen @ 3.0 GHz || 768.0 GFLOPS
Per Digital Foundry a Raven Ridge APU (4 Zen cores, 8 threads, 3GHz, 14nm) can deliver 60+ FPS in CPU limited scenarios where the PS4 Pro (8 cores, 8 threads, 2.1 GHz, 14nm) can't maintain a solid 30 FPS.
It's worth remembering that the Jaguar microarchitecture was fundamentally different from Piledriver or Steamroller (AMDs Desktop CPUs at the time). Whereas all the Ryzen Mobile APUs released so far are identical to the Raven Ridge Desktop APUs (like the Ryzen 5 2400G), just with different clocks and different features or parts of the chip disabled. PIledriver and Steamroller cores could perform three times as many single-precision floating-point operations per clock as a Jaguar core (or three-quarters as many as Zen).