Even if you are right and it gets as low as 12,000 by 2021..it could easily get to 26,000 again before then..
My opinion is that half the damage of worst case scenario has already been done and it could take another 9 months or longer for the bottom to be reached (worst case ) ..in that time there'll be little good runs.
Again that is worst case..we may have already seen the bottom for the next few yrs .if we knew for sure we'd all be billionaires