From my understanding, when you start powering down, you still have Vests, so you still have a share the 9:1 steam going into the vesting pool. The amount of Steem that you get each week should increase. In the end, you are going to get much more Steem than what you put in. You can hope the market does not plummet faster than the slow increase in the amount of coins that you receive each week.
The whole system seems too complicated and I did not have enough time to study it properly (recently registered on their platform) and I doubt I will have any good content to publish there soon.