The housing, pedal and some electronics are common. The little coloured peice with the knobs on it is interchangeable. Personally, I'm struggling to see the need for this. In another forum it seemed like a good idea for beta testers, because the manufacturer could just send the module to them rather than the whole pedal... but even that seems like a lot of mucking about for a small gain.
It says something about ''if the screws are undone''.... why would you want to leave them undone? Out of unplugging the things or getting out a screwdriver I know what I'd choose.
Well with the screws out it has a locking pin so the module is still secure, just not as secure. Interesting things could be like they said changing your effects line up, say you have 5 tonecore pedals and the compressor is before distortion and you want to try it after distortion so don't need to rewire your pedalboard to do so. You might even need to do something like this inbetween sets. Another thing might be say you have 2 tonecore pedals and only need 1 at a time on a gig, you could swap the module out even as easy as inbetween songs, not saying this is the most practical but it could work. I presume it also makes replacements quite cheap, such as if you broke the footswitch but not the module line 6 could send you a footswitch and you can change it over yourself. Whether or not it is practical is another matter, I just thought it was interesting.
I wanted one of those SOOO bad. Who knows, maybe Line6 has something up their modular sleeves. What if their sleeves zip off and you can put short sleeves on instead? Whoa.