> The 604 core was a deadend at Moto/Freescale/name_of_the_week,
> all newer CPUs/SOCs can be traced back to the 603.

The 603 lineage stopped with the e300 (MobileGT / MPC512x and PowerQUICC II Pro / MPC837x) and the e600 (MPC7448 / MPC86xx) short of a decade ago, so has turned out as a dead end as well. The MPC8xx / MPC5xx / e200 and e500 lineages (including e5500 / e6500) which the newer Qorivva and QorIQ P/T (as well as older PowerQUICC III / MPC85xx) are based on are not derived from the 603 / e300 / e600 lineage.