Rewind N years and you can replace PaaS with some other technology that eventually matured and is now considered ubiquitous.
"You run your site on an 'application platform' like Heroku, Azure, or Google App Engine. You design your application around whatever metaphors and APIs the service lays out, and in return you are veiled from all the mysteries of implementation. You never interact with the computer directly, but upload your code to the platform with the proper incantations and it runs. The orders vary in strictness, with GAE requiring that you purify yourself of all worldly design habits before writing your app, Azure insisting you renounce the demon Unix, and Heroku somewhat more welcoming to the fallen. On all three platforms, when your application needs more resources, you press the 'more resources' button. A lot of fancy sandboxing, monitoring and administration tools come standard, and it's very easy to deploy and test different versions of your app."
Pinboard's point of view is vertical within a single organisation, whereas Gigaom's is horizontal across an industry.
I think the whole point is the developer no longer have to be concerned about the day to day management of the server (e.g. tuning disk I/O, manually deploying applications and services, setting affinity on processes, managing logs), as that will be shifted completely to the infrastructure managers. And that is fine. Infrastructure should be devolved completely back to the administrators and developers should just write code that runs automatically with no modification in the cloud.*
I am not sure what the last question supposed to be, but I assumed it implies that systems administration will be obsolete. It is possible that it will change,but consider this: in the past, most sysadmins worth their salt should at some point be able to write code. It is only recently (it seems around the late 90s) that there was a generation of admins that didn't have the technical chops to write code or even simple scripts. With the advent of cloud and the management tools that comes with it that requires a significant programming background to manage (e.g. writing Puppet or Chef code), this is a welcome return to the past.
*In theory. :)