So, you're finally gonna do it. You've been talking about ripping this 3rd side off in about 9 other threads 
Are you going to integrate the ripped off cp into another cab?
I'm going to smash the CP into tiny little pieces, light it on fire and then and bury the ashes in my back yard.

I doubt the CP will be salvagable - maybe the panel with the button holes but I don't think I'll have another use for it. I don't even like the layout.
The other thing I was thinking was you could turn that hole into a lit-marquee area.
I noticed on your blog you named your cabinet Knights of the Arcade Table. I just grabbed the Knights of the Round title screen and pasted in that spot.

Just another thought... 
That looks sweet. I'm thinking about it. If I can't get a piece of birch veneer like 1/16" or thinner to cover the hole (that I will patch underneath with plywood) I might go the marquee route. I'm hoping I can stain the veneer to match and then it won't be that noticeable. If I can get a piece the size of the entire panel then even better but I don't know where to look for something like that.
EDIT: I found a source online but it is
EXPENSIVE. I'm also not sure how I'd glue it down to the surface evenly. A piece of MDF and a few cinder blocks for pressure? It's good that it is on the long side because I'll be able to use my router to get a perfect fit around the edges once it is glued in place. The t-molding should cover the edges since the original plywood is less than 3/4". I think this is going to work.