IIRC, Sony was banking on the PS3 being a 10+ year console. This could all change with the discovery of the PS3's private key however. Of course if that's the case, the PS4 might just be a PS3.5 with a new private key.
As it's always been said, idea's are a dime-a-dozen, it's the implimentation that counts. If someone copies you then you just have to out do them with better features or support. My feeling, is if you're trying to prevent someone from competing with you, you may win in the short run, but in the long run you'll probably lose.
By trying to stop other people from competing against you it diverts your time, energy, and resources to something that could be better used to make your product better. Lets say you are successful and you stop the person from competing directly with you, two other projects might pop up that do the same or similar tasks that your project does. Now you'll have to go after them, ad infinitum.
Next, while this won't affect your customers it may affect your investors or possible community which you have gained. Some people may take your attack as being childish or as being a weakness to your person. Your reputation may suffer as an end result and you'll lose the confidence of your investors and the community you built up may leave because they don't like your attitude.
It's a touchy subject and I'm not the most knowledgeable person as I've never really been in this situation. However, I've always felt it's better to just push on. Competition is good for you and the customers. While you may feel like it's harming your bottom line, you'll probably end up with a much better product that will prevent a much larger corporation with much more resources from entering your market bruteforce because you have a battle-tested product with a good amount of features.
I don't think applications will be as much of a problem as you think. As with a lot of open source hardware project it's only a matter of time before you'll have a community backing it. That means, a lot of the Linux applications will be ported over.
Also as another benefit of this using an ARM processor and a lot of netbooks and other hardware going the way of Linux this is good for the OS side of things. Windows won't go away and I wouldn't wish it to as it has it's place in the computer market, but getting people away from the Microsoft way of doing things is a good thing. Either through Apple's hardware or these open source hardware projects will slowly eat away at Microsoft's market share. It's an uphill battle and won't be over anytime soon but I like where it's heading.