Hi,
there is no firmware/software update that can allow this. You can’t daisy-chain units with USB, so when using two units as stand-alone you will always be limited to the facilities available on the master device, i.e. 8 analogue ins and outs 2x ADAT ins and outs (plus the phones outs).
I’m not in the position to reply extensively to your questions, but I’m not aware of a discontinuation of this unit.