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develop software on the PS4, you won't see nearly the offensive to crack the system open apart from proof of concept, unpublished or artificially limited exploits.
It's unfortunate that the attention span of most users is as short. Aside from the Linux issue, the PS3 was decidedly hostile towards small game companies for a very long time (ridiculous development system costs, year long approval process etc.).
That said, in the case of Other OS, I'm pretty sure the only reason they got away with it was because almost nobody used this feature. Indie games would hopefully be more popular, and hence harder for them to back out of.