That's probably a bit overstated. Many, many companies are completely dependent on the Microsoft framework or the Oracle/Sun framework, yet there is not an issue with that.
The bigger issue is they are dependent on frameworks that are still evolving at very high rates. Rapid changes brings a lot of chaos into the equation, which is dangerous from an investment perspective, but that same chaos can lead to unexpectedly strong results as well.
But the difference is they're not dependent on the Microsoft presence. If Microsoft ceased to exist tomorrow (localised meteor strike, let's say), the code running on .NET, Windows, etc. will still work. If Facebook is down, so are you.
That isn't really true. If Microsoft somehow ceased to exist, business would switch away from Windows and products written exclusively for that platform would be toast. The difference is really that for internet/cloud platforms, temporary outages can lead to lost revenue--which everyone developing apps on those platforms hopefully recognizes, especially given Twitter's former reputation for instability.
But the switch would not be immediate, a least giving providers some time to move to other frameworks. As you say, from a slightly different angle, it is the immediate effect that is the problem with relying on facebook or a similar network for your business: if they fall over tomorrow or simply change their rules so your product does not comply, your revenue stream stops that instant and until you can design and implement changes in the product or business model.
I doubt many businesses that have built and scaled their infrastructure on Microsoft systems would overhaul their entire operations just because Microsoft itself disappeared. Consider the amount of legacy systems still in use in large enterprises today; many of these were originally designed by companies that are long gone.
If anything, the collapse of Microsoft would produce many smaller companies competing to satisfy the ubiquitous demand for Windows support.
Yes it's true that your products wont stop functioning in the short term, but a dead framework that's no longer supported and updated means you HAVE TO rewrite it using another framework. and we all know how costly rewrites are.
I find the 2 scenarios you listed to have much more in common than not. The main difference is the amount of time you have to react.
> Many, many companies are completely dependent on the Microsoft framework or the Oracle/Sun framework, yet there is not an issue with that.
The difference is that if Microsoft of Oracle/Sun disappear, the framework does not.
There is another rather unhealthy (IMHO) trend in the market today for DRM to be applied to everything. That can mean that products consumers have paid good money for can effectively just be switched off arbitrarily, and that's why I don't personally buy things that are DRM'd in such a way.
Developing for mobile platforms can be similarly risky. For example, my startup has no current plans to build an iPhone app, even though our users might appreciate it. We simply don't trust that Apple will not just arbitrarily squish us and not even notice/care based on their track record to date, and we would rather invest our money in safe platforms like the web. Apple aren't going to stop shipping a browser that can view modern web sites, it would kill their products.
The bigger issue is they are dependent on frameworks that are still evolving at very high rates. Rapid changes brings a lot of chaos into the equation, which is dangerous from an investment perspective, but that same chaos can lead to unexpectedly strong results as well.