Sony dangles these features like candy and they can take them away on a whim, but I don't think it will happen this time. Sony took away Linux because they were scrambling to plug any potential hole that would lead to piracy on the PS3.
Aside from curiosity, the foremost minds that opened up (jailbroke) the PS3 were motivated because of the lack of homebrew support -- the ability for hobbyists to run unsigned software on the PS3. Getting license to and legally develop for the PS3 is simply not a viable avenue for most people. Sony appears to have their bases covered this time in showing their support for indie developers. If it is easy, and most importantly accessible to develop software on the PS4, you won't see nearly the offensive to crack the system open apart from proof of concept, unpublished or artificially limited exploits.
Aside from curiosity, the foremost minds that opened up (jailbroke) the PS3 were motivated because of the lack of homebrew support -- the ability for hobbyists to run unsigned software on the PS3. Getting license to and legally develop for the PS3 is simply not a viable avenue for most people. Sony appears to have their bases covered this time in showing their support for indie developers. If it is easy, and most importantly accessible to develop software on the PS4, you won't see nearly the offensive to crack the system open apart from proof of concept, unpublished or artificially limited exploits.