Infrastructure software isn't dead - but Openstack is.
It may still be used, and may continue to see a bit of media now and then but really it's gone the way of Puppet/Cfengine/<many proprietry infra software here>.
It missed it's chance to be good by allowing itself to be corrupted a massive design by committee disaster. Openstack needed a cohesive vision if it was to stand a chance against the integrated enterprise stacks or the custom in-house ones it sought to supplant. It never had it and at this point it never will.
I don't mean any ill-will to any of the Mirantis boys or the other countless hackers that worked on Openstack circa Cinder/Neutron introduction. I was there too, we tried to right the ship before it got too far off-course and we failed. Many smart people tried to make Openstack good but it was out of the hands of the hackers.