There aren't any details, but we can make some assumptions. Assumptions sometimes turn out to be incorrect, but at least these are semi-educated guesses.
Assumption 1: AX8 will send (and respond to) PC messages per preset. FX8 offers this ability, and it isn't specific to amp control like the FX8 relays.
Assumption 2: AX8 will feature a MIDI block. It's not just an Axe on the floor, it's also a controller. So as with the FX8, I think it's reasonable to assume that it will provide at least basic MIDI control of other gear. With scenes and the current MIDI block iteration in FX8, you can send 2 PC messages and and 1 CC per scene. In a preset with a MIDI block, you can have the main preset PC message (to the FX8 channel), up to 8 scene PC messages (1 per scene), up to 4 PC messages with the block (PCs for block X On, block X Off, block Y On, and block Y Off), and up to 2 CCs with 2 different values (CC X value for block X On, etc).
The number of simultaneous different PCs per scene is currently 2, so programming a couple other Strymon pedals with FX8 (and therefore AX8?) would seem easily doable. Add any more devices, and you'd have to start planning the preset orders on the external devices to line up.
Assumption 3: I think we can safely guess that it won't send tempo. No Fractal product currently has MIDI clock output. You'd be better off with a Disaster Area or Molten Tempode. The AX8 could still be your brain, just send PC messages to the master MIDI clock and let it send out tempo to other devices.
Disclaimer: any of these assumptions could turn out to be wrong.