There's only one block remains before next difficulty and suddenly everybody stop mining and wait for the 14 days to lapse. Let the next difficulty to readjust lower, then everybody start mining again the next 2016 blocks without an increase in difficulty. Rinse and repeat. Of course, not possible in practical..but what if?
14 days is the time taken by bitcoin system during an 'ideal' condition for all 2016 blocks to be mined out. Anything less, difficulty will be readjusted to match the global hashrate to bring it back to 14 days cycle. Anything more, difficulty will be lowered accordingly. Unless my understanding is wrong :S
The 14 days IS the 2016 blocks. There is no time ticking by (other than for timestamps). If you stopped at 2015th block, it wouldn't readjust until the 2016th. Then it would take the average time of all 2016, and set the new difficulty so that the *average hashrate* of the previous 2016, results in 10 minute (avg.) blocks.
There's nothing to be gained. Either the average increased, or decreased, or stayed the same, but it makes no difference if it's 10 TH/s that works full time or 100 TH/s working 10% of the time. The difficulty will be the same.
