[citation][nom]CaedenV[/nom]SSDs are the #1 reason for a lack of new PC sales. You can buy a whole new computer (without an SSD) for $5-700... or for $1-300 you can have an SSD installed in your current system and have everything transferred over, and have a system that feels like a new machine. That is some pretty simple math, and if PC makers want to move machines then they are simply going to have to make SSDs a standard feature, or at least a hybrid drive if space is a concern.[/citation]
SSD upgrades are probably down in #2 or #3 spot for decline in PC sales.
First, tablets. With a decent sized screen, many are using these for basic web browsing, tweeting, online shopping etc. Thus, less need for a 2nd PC or Laptop.
Secondly, Tell me your "old" dual core machine with 2-4gb RAM isn't fast enough to do the same basic tasks that make up 90% of what people use computers for. (You average user has no clue what photoshop rendering speed, zip compression, video encoding fps etc. are, and they probably use a console for gaming.)
So we get down to the SSD upgrade and OS reload scenario. Most people don't know what the heck us geeks are talking about when we start spouting that off. And, I don't see comercials for the geek squad touting the need to upgrade to an SSD. (They'de rather sell you an iDevice anyhow) So it is hard for me to except this as #1 reason for lack up pc sales. But - I do agree with you, for those in the know this is the way to go.
My own analysis of why pc sales are stagnating has more to do with software than ssd sales. The world has taken a step back by 10 years on the software front due to the limited hardware capabilites of mobile devices. Traditionally, we have seen the need to upgrade every 2-3 years due to advances in software needs. But the market has stagnated with dual-quad core. We need to see some killer app that is power hungry and needs to be fed more cores to see a surge in pc sales. The problem with that, is the heavy lifiting is now done in the datacenter with most apps these days. So who knows when we'll see the need for more power in the desktop.
As far as SSD goes, I can see these replacing spinning disks soon for basically the same reason as I stated for CPU power. Everything can be stored and shared via a datacenter, so there is less need to have a ton of GB locally. (Unless you care about privacy, and security of course).