I could be wrong but I think it’s mostly routing, which should be achievable via a firmware update. The only hardware limitation I see is that there might not be enough FX processors if each output needed a separate processor to achieve truly independent mixes, but they could get around this by allowing us to assign shared FX channel to an individual mix.
Personally I only use 2 FX channels for reverb (which could even be reduced to 1) so I could have 2 channel used for my Main LR, and 2 used for my monitor mix and this would perfectly suit my needs.