And for whatever reason, 95% of the hash power is taken off the network (which is NOT totally unrealistic. If there's a rise in electricity costs
A sudden, instantaneous rise in electricity costs across the entire globe all at once to levels that cause all but 5% of the miners in the world to immediately shut off their equipment? You consider this "realistic"?
or a decline in bitcoin prices to the point where power cost > value of bitcoins mined, a lot of ASICs will be taken offline, since even if you wanted the bitcoin, it'd be cheaper to not run the ASIC and buy the bitcoin instead).
If 95% of the miners shut off their equipment, the remaining miners would see an increase of 20 times as many bitcoins for each block that they solve. This increase in reward would attract additional miners that either have access to very cheap electricity, or who aren't very good at math, or who put a premium on the idea of not dealing with an exchange to acquire their bitcoins. These additional miners would result in an incremental decrease in time between blocks.
The difficulty is still the same, and will remain the same for 2016 blocks. If 95% of the GH disappears, then each block will now take 200 minutes to find on average, for the next 280 days.
True, if that many miners all shut off their equipment, and there was no addition of miners from anywhere in the world, then blocks would be slow for a while. If a significant enough percentage of bitcoin users became seriously concerned about this, a new client could be released that would temporarily reduce the difficulty. The bitcoin network/blockchain would fork if 100% of the users didn't switch to the new client, but if it was a serious problem, it should be possible to get 90% or more of the network to switch.