Information Technology covers an incredibly wide range of careers, only a small portion of which are system/network administration related. Yes, in some organizations, the "cloud" may reduce the need for traditional SAs, but it is simply the latest in a long-term trend of reduction in force for that sector.
Automation has already decimated the SA workforce. Long gone are the days when companies needed armies of SAs to maintain datacenters of servers. The datacenters are still there, but are being maintained by much smaller teams of SAs using automation rather than manpower. Many large corporations who haven't (and won't) embrace the cloud, have already gotten rid of their SA staff, relying instead on vendors like HP to provide both hardware and SA level support as a bundled package. There are still SAs, of course, but they increasingly work for one of the main vendors, rather than being distributed throughout many corporations.