On a personal computer, there is free software to accomplish any desktop computing task. How can you say that it wont get built when it already has been?
That will not automatically happen for a lot of classes of software. You point out that any desktop computing task can be done with free software. So what? That doesn't even matter anymore. It's 2014 and we can't accomplish a significant amount of mobile computing tasks with free software, and those are more intimately connected to us than desktops ever were.
You make an excellent point about mobile computing. However, interest in free mobile software is growing and we'll see more options available to mirror the demand.
What I'm trying to say here is that I hope to see even more business models that work well so we can get free alternatives in more areas of computing sooner rather than later.
Meanwhile, the closed systems people do pay for have a monstrous advantage and will continue to be far ahead. Nowhere are they further ahead than design and user experience, which in my experience are harder and more work to get right than core code. When you make something work you are only maybe 25% of the way to making it usable. That last 75% is the no-fun stuff people have to be paid to do, and it's the stuff that separates products people use from geek projects only a tiny number of enthusiasts play with.