According to this, it is almost certain that South Korea will withdraw from dressage.
With Hwang Young-shik no longer aiming for Tokyo and Rio 2016 Olympian Kim Dong-seon retiring from sport last year, South Korea is left with a couple of amateurs with no realistic hopes of achieving MER. There is still some time left, though.
If Korea withdraws, Malaysia would receive a reallocation. It seems like Qabil Ambak is feeling pretty confident about this, as his horse Delatio got transferred back to Malaysia just before the horse nationality cut-off date on January 15th. Ambak himself has not competed the horse for over a year now.