Doesn't look like will be hack.
Seems will be stuck on 5.05 lol.
I'm sure read hackers have got hacks for firmware 6.0+. Maybe scared of releasing because of sony.
Think you're right, I reckon any exploits will be sat on until the PS5 comes out, afaik mathieulh had a 5.50 exploit and likely later, FailOverfl0w (sp?) also found an exploit on some part of the HDMI interface which obviously wouldn't be patchable unless a whole new board was to be produced.
TL;DR be patient
Edit: I'm lucky in that the only update I ever did was to 5.05 and no further, can play any game released before march 18 but there's a lot of games I'd like to play RDR2, even having the VR as well my PS4 rarely gets used, occasionally play mega drive games tho