John,

Since the 562V is positioned as the Audio/Video switching unit they could remove the video in/out from the 568.
This would leave ample room for extra analogue inputs. And yes, you would need extra A/Ds, but there is plenty of room in the box.
And A/Ds are not that expensive.

Another option would be to have the multichannel link switchable between digital and analogue input processing.
Then you would just need a convertor cable (and extra A/Ds).

Regards,
Mark