It may be next CPU board imply more performance but it may be not the case, nor it is the only nor more important point.
Newer SOC may be more efficient (less battery consumption and less heat for same work), be 64-bits, run cooler (and then run at top speed more time until it has to throttle down), have actual support for more OS, newer drivers, more open documentation, more "freedom" (i.e. less undocumented and obscured parts)... There are a lot of points other than simple brute performance.
Think for example «
OMAP5 software support stopped - old drivers from TI don't work with modern kernels and as the OMAP5 is not used in any other public Linux device, there's not a lot support either».
And it can be cheap for the SOC itself and for board cost (ED words:
OMAP5 is around 50 EUR... more layers and made the design 10x more complex ), so that point is important too.
If you are interested there are unofficial threads about CPU board upgrade. For example:
https://pyra-handheld.com/boards/threads/the-future-of-pyras-cpu.80526/
but they are "unofficial", i.e. us talking with imagination