I've been doing systems work for quite a while, and The Cloud isn't making things easier for IT workers -- it's making them more complex as there are now more moving parts you don't control to consider. Our company is still mainly an on-premises shop because we deploy stuff in areas where The Cloud can't be accessed at a reasonable speed for a reasonable price. But, I would say that virtualization in general has made things a lot more...fluid...than before. What's needed now is more people who know integration and the end-to-end nature of a system. I'm not talking about master black belt CCIE MCSE RHCE whatever savant experts...just people who have the ability to break a problem up into parts, troubleshoot what they can, and know who can help with what they can't.
In previous days, you had the Storage Guys (or Girls) that would do the magical incantations to convince a SAN to provision a LUN to your machine, the Server Guys who would manage the operating system, the Application Guys who would manage the program running on the server, the Network Guys who did all the connectivity magic, and the Data Center Guys who would install and fix physical equipment. Each one of those was a specialty, and still is to some extent. But, as more and more small VMs can be squeezed onto fewer and fewer boxes, there's less of a need for an infrastructure guy. As storage gets more virtual and easier to self-provision, the storage guys become more of a commodity. And if your company goes AWS, Azure or similar, all those Guys get replaced with a web interface and it becomes someone else's problem. I'm still totally amazed how many machines fit on a single HP DL380p physical server compared to what was possible even 5 years ago. And the public cloud services are even more interesting -- multi-football field size isolated rural data centers with thousands of machines and 4 employees to swap parts/install more nodes.
I think the future in IT is going to be less on the front lines and more cross-specialty, regardless of whether your data is onsite or offsite. In house coders are probably going to have problems because every single company is being sold the cloudy Salesforce or other ERP system as the cure for all its ills, so dev jobs are going to shift more towards software companies. Infrastructure guys will still be needed, but they'll be working at a higher level doing design/architecture rather than physical server management. There will still be analyst and project manager jobs, but I think those will be even less technical than they are now. Analysts will solely be an interface between "the business" and "the cloud guys". PMs will be secretaries who beg people to get things done. Add in the constant threat of offshoring, and salaries are definitely going to drop. I think they're probably going to go bimodal -- even lower pay for basic tasks, but similar or maybe even more pay for engineers/designers/architects who can successfully make the transition.
No one is capable of stopping The Cloud. The vendors will continue to sell companies on how wonderful it is, and the companies will find out after a while that it costs too much to get their data back and rebuild their own capacity on-site. I'm just hoping that good people will be allowed to work remotely so there won't be some massive migration that IT guys need to do to survive.