As with any productivity boost - if you need 100x fewer IT jobs, it doesn't mean you will cut your IT by 100x, you will instead increase just grow your IT department 100x or however much until you hit a growth bottleneck on the business side, then some jobs will shift there.

Just like my raw materials/energy cost example before, if you something becomes cheap - you don't consume less of it, you try to do more with it. Maybe, so much more that you can now do things which were completely impossible/unaffordable before!

It's very possible we will have MORE IT jobs due to new opportunities and efficiencies.

A decent software developer costs $40/hr. Let's say you can make your small iPhone app idea in 100 hours, that's $4,000. If developer with 100x as productive, now that costs only $40. That doesn't only mean more people can afford to build their ideas, but you could build BIGGER ideas, on a $4,000 budget you could now build $400,000 worth of an application! Think of all the opportunities for everyone!