I know you need to replace OCI at a certain age, not sure about PIO.

However, a PIO isn't really deemed 'equivilant' - PIOs are being deemed valid for 'lifelong' supposedly - only those that existed prior to the change. The change was no new PIOs will be issued - if you need to get another one, you need to get an OCI.

Based on feedback here, it seems like some officers, and I know my experience in talking to CKGS, was that you need an OCI. I got one, because the hassle of applying for an OCI from a PIO once was likely going to be less then the likely hassle I'd get for using a PIO to enter everytime going forward (you need to switch to PIO, etc.), plus I knew it was just a small fee compared to doing it for full price later. Of course, all this is based on the fact they don't change the rules again - but good luck with that.