Commodotisation
Let's talk first of the commoditisation process. The commodotisation is the process from which an innovation (Computer Aided Design), becomes a Bespoke product to a Product (CATIA, NX, Pro/E,...). It predicts as well that the product will be considered a commodity. Like electricity.

Electricity, I like this analogy... who still buys its own engine to produce their own electricity? When you need electricity, what do you do? Do you go to the grocery store and buy some? Or do you plug your computer on the network?
I firmly believe that this is what is going to happen with CAD and eventually 3D design. It is just a matter of time. Some PLM companies have started their "Cloud Computing Strategy"... Dassault Systemes has launched 3Dvia shape. You can design 3D models and save it directly on the website servers. Is that cloud computing? Only partially because most of the computing is done on your own computer. It' s not even SaaS, because the only service proposed is the storage, not the all software (I hope one day I'll be able to explain why SaaS and cloud computing are not the same thing). So what would be the next steps?
The Technology
Let's take the view of the customer. As an big industrial, I have thousands of machines that I have used for CAD along the years... and I do not know how to leverage all that "dead" material. CAD becomes more and more complex and require more and more resources, therefore more powerful desktops for designers. As an IT manager, I am tired of plan for upgrade of my material and of software on each computer.
What would be life if instead of using computing resources from one computer, I would leverage computing resources of my data center?
Today, the technology is here, and surprisingly simple.
In order to reduce my computing resource to a minimal, I could just be transfered the video flux from a server. You'd connect to the server via a seamless virtual instance that runs your CAD application. The server takes care of all the rest, the calculation, graphic acceleration,...
And for company that do not have data centers? Then they can go a a public one, provided that the data is secured and persistent.
For companies it would be a huge benefit to share their licences, optimize the existing material (if the only thing that is done by your computer is to read a video flux and interpret mouse click, a simple browser can do the job! Unix, Windows, HP... any computer with an Ethernet plug could do it).
Migrations and Upgrades will be simplified, or even become seamless on the public cloud controlled by the PLM vendor. You just have to do it in the data center and replicate the virtual machines...
The Business Model
But then, comes the money. How can one monetize this approach.
Think Amazon. Amazon sells computing resources. Dassault, Siemens, PTC could do the same... (or they could buy computing resources from Amazon and resell them). How does amazon bill their customers? by the resources used for computing, by the resources used for storage (and of course the CAD added value).
I honestly do not know if there is more or less money to make for the vendors (probably less), but the impact on the market will be huge for the first one who will make the jump. And if it is not a PLM vendor, it could possibly be one of their partners. What would prevent them to buy computing resources to Amazon, buy concurrent licences to PTC and leveraging them 24/7 with such an approach. Nothing.
The video game industry already started. Check OnLive.com. And OnLive is not a video game software company. This is not any different from what I am describing. And they have similar computer resource needs as CAD.
As I said, it is just a matter of time, and whoever makes the jump the first, the others better be ready because it will be a significant earthquake in the PLM industry.