One important thing to keep in mind that is not mentioned much regarding SDN and its threat to CSCO is that Software Defined Networking (SDN) which runs on cheaper boxes will be a subscription service, this may hit Routing and Switching vendors over the first few years, but over the long term, I gotta believe it will more than make up for the lost sales in the high margin hardware.  This is a point not highlighted by analysts that are fretting over CSCO's future.

IMO, if anyone can make that transition well is CSCO.

Similarly, NOK now has a strong presence in the SDN arena via the ALU acquisition.