Itchy butt man,
The CF scenario in my airline is based on the most limiting of the three scenarios too.
Engine failure at CP with drift down to SE cruise altitude.
Depressurisation and flight at 10k
Engine failure and depressurisation at CP.
I suppose you could say the plan is refiled from that point assuming the VR hasn't been burnt and is available.
If you've burnt the fuel then you didn't add enough fuel to cover possible enroute weather deviations and taxi fuel when busy.