Comparing a cloud outage to a power cut ? Really ?
That's like comparing theft to copyright infringement.
If your problem is power, then what you need is a backup diesel generator (or however many are required to cover your needs). Insert it into the grid, fill it up, put it on standby and you're done, apart from the regular maintenance and trial runs. Frankly, apart from the cost, this is a no-brainer operation (and yet, some still manage to fudge it up anyway).
That is peanuts in price and hassle compared to a cloud outage. Even if you do go for a backup cloud operator (and we're talking big budget operations right there), there will be a boatload of problems to deal with on the spot when (not if) it happens.
There are internal procedures to devise, which will need to be amended after the first live-fire event (because there's always some difficulty that was not taken into account).
There is (company) user training, because said procedures need to be understood and implemented in an urgent situation. There is proper warning and communications, because the switch cannot be made before it can be, and (company) users switching manually on their own willy-nilly is going to create its own special brand of havoc.
There is monitoring that the switch has taken place and that operations are once again in a working state. What are the metrics ? How to measure them in a time of crisis ? How to ensure that all required functions have been taken into account ?
Finally, there is recovering from the outage, and the decisions that need to be taken - mainly do we switch back again, or do we only switch when this cloud fails ? After the first live-fire event, maybe previous policy decisions will be reviewed in light of performance before and after the switch.
Then there will be the accounting fallout, because all of this hoopla will be quantified and cost-assigned, and the next board meeting will be a live-fire event of its own.
No, comparing with a power cut doesn't even begin to do this kind of thing justice. It is a very poor comparison.