Mathieulh has made a few statements in the past few days/weeks that are completely clear:
1) A group of hackers (himself at the very least) have access to kernel exploits (or better) that Sony haven’t patched yet. He’s proven it by revealing some content from the 5.55 kernel a few days ago.
2) There’s no planned release of any exploit for firmware 5.50 or above, that he’s aware of. Again, given how spot-on he’s been recently, that’s probably as good a prediction as you’re going to get for the time being.
Of course, nothing’s impossible. My experience on the hacking scene tells me a PS4 exploit for 5.5x will happen eventually, but it’s hard to tell “when”. Given how recent the 5.05 exploit was, my personal opinion would be that people who want to jump on the hack bandwagon sooner than later should try and get a PS4 running 5.05. If those are getting too expensive for you, my second suggestion is: buy a second PS4, and keep one on a shelf until the firmware it’s on gets hacked. That’s what I did for 4.05 (it waited on a shelf for about 16 months).