As Cyb already seems to have a problem with someone blocking the SupCom spot without beeing active, how about this:
The SupCom can level "down" to another Rank (might Rank 7,5 or even Rank 9) called something like "decommissioned Supreme Commander" (might need to be shortened a bit) where is no number-restriction.
This way the Supreme Commander can free the spot for someone new if he expects to be a bit inactive - without having to get killed and lose everything. This might also be done automaticly if the SupCom was inactive (need to be defined if inactive is not playing games/not attacking on GW or not gating into GW) for a certain time.
Might should be possible to go back to the SupCom spot if its free - not sure about.
In difference to the SupCom, a decommissioned Supreme Commander is not able to use use the "final weapon" (which was annonced if I'm right). Not sure if anything else should be cut.
Any thoughts?