JTAG's the extreme case though: it's not like most existing hacks have involved that level of access. It's been mundane stuff like just going in through the USB interface. If Apple eliminate the USB interface entirely, they're still going to have to make it available by some other means to service/update the device. Which means they'll be adding that software stack to wifi/bluetooth.

Your 2 attack scenarios are: device is in evidence lock up, and can b cracked at will (so a security company probably comes up with a kit for cracking and hooking them up, sells the service to LE) - or what happened with T2, where the software stack just gets exploited.

Since you'll still need all those management interfaces that currently are only on the physical port to be somewhere - well I'd put money on removing the port actually making the device more vulnerable. Briefcase of GPUs to crack wifi and rootkit a phone if you can get on the same network.

My sense is that existing physical access exploits have relied on legacy assumptions that shouldn't exist for wifi/bluetooth - hopefully no-one is building systems that give wifi devices direct memory access, or boot over bluetooth. They'll need some level of management interface, certainly, but that's likely to be something purpose-built and more tightly constrained.