re: They can only control the orientation if the gyros hold out
Yes, I was thinking of Dennis Wingo's company (Orbital Recovery) when I wrote about attaching a deorbit booster.
I wonder if an electrodynamic tether propulsion system wouldn't be a better idea for reboost and deorbiting. I imagine you would need to add some solar panels in either case.
http://www.tethers.com/EDTethers.html