Earlier quoted context omitted.
IPv6 makes the global routing table much smaller (because there's enough space for the subnets to be logical parts of the network, rather than squeezing as many addresses in as possible), so the core routers for the IPv6 internet ought to need less hardware than the IPv4 ones.
Ah thanks! Does this mean that the end routers can be simpler too, or do they still need significant processing power?
IPv6 also deals better with packet headers, so it's easier to calculate for routers. I suspect however this will make more of a difference for high end routers with lots of traffic.
As others have mentioned, the dual-stack transition does require more resources. Then again, you can implement NAT64 (or 464xlat), which seem to become more realistic/robust/more widespread solutions (running dual-stack also means managing two layers of routes, two layers of firewalls, etc).
(Disclaimer: this is not my day job, I just find it lots of fun to play with on my local network and the Montreal local city mesh.)