the higher-end switches take considerable engineering, just on the hardware side, and are fairly high-margin products. If the networking equipment space becomes OS agnostic, or consolidates around OpenSwitch, this removes one of Cisco's major advantages (their huge installed-base, network OS dominance, customer switching costs), and allows HP (and others) to compete directly on network equipment hardware architecture/performance/cost. More competition in that area would be a very good thing (maybe not so good for Cisco's dominance). It's also good to decouple the hardware from the OS/software, and allow innovation in both areas independently.

Candidly - their switches in my experience are garbage. They aren't making money, and they know they can't beat Cisco with a traditional approach. If I had to guess they're hoping that opening things up will make them the vendor of choice for enterprises looking to mimic Google/Facebook. This feels like a hail mary with the future of their presence in the network switching space to me.

If this becomes the main type of switch, then HP would be in a great position to offer integrations and consulting.

"all of the above" is probably the correct one :)

Selling software for central management

Its probably aimed at bringing Cisco's revenues down.