You still need to communicate with other DNS servers - which ideally would be close.
This brings up a related issue. DNS resolution is one of the biggest problems with Kenyan Internet. The Google/OpenDNS nodes are off-continent and because the traffic is UDP, are highly susceptible to the packet loss problems discussed last week.
Having just one major anycast DNS node in East Africa would be a "big deal". Having that node be a primary DNS server for local ISP DHCP configurations would be an even bigger deal.
By major I mean one with enough queries that the cache hit ratio is up above 50%. This is more of a problem these days because everybody is using short TTLs for their records ... which means that the cache timeout is low and you need alot of traffic to not be constantly going to authoritative name servers which are far away.