Can I flash to a Particle Photon wirelessly?

Is it possible to flash new code to a Particle Photon without access to the physical micro-usb port?

Yes. That is the main draw IMHO of using the Particle platform. I routinely flash new code to a device running at home from my work PC many miles away. The Photon does need to be connected to WiFi before trying to flash anything Over The Air (OTA).