one thing they may lose
The only value I saw HP might get out of their public cloud is experience at some scale with Openstack (they said as much themselves too last year). HP's public cloud (as far as I was told) was mostly built by ex-rackspace people (since rackspace shifted focus away from openstack a few years ago to more managed services etc) who were upset with Rackspace's change in direction.
When HP announced it, I ripped into them myself since they adopted many of the same broken designs that Amazon and others had been offering, biggest one was provisioning.
I never used HP's cloud but I did use amazon's for a couple of years, worst experience in my career. Never again. I don't have any higher expectations for google's or microsoft's cloud either.
IaaS in public clouds is simply broken by design. Maybe PaaS is better in that respect because it can mask some of the deficiencies of the broken IaaS. SaaS public cloud seems the most mature, masking even the failures of the PaaS and IaaS. But of course as you move from IaaS to PaaS to SaaS you lose ever more flexibility and control, for some that is a good thing for many it is probably not.
To-date the only model I have seen give actual good results is SaaS, but of course the scope of products in that space is relatively limited. The company I work for has moved off of multiple SaaS platforms to in house solutions because the SaaS wasn't flexible enough.