Square Enix has announced on their site that the Japanese voice actor for Olaf, Pierre Taki, will be replaced in a future update for Kingdom Hearts III. Taki was recently arrested with using cocaine. Disney has already announced they are looking for a replacement for Olaf for the Japanese release of Frozen 2, which is set to release later this year.
His replacement and a date for the update patch has yet to be announced. The patch will only be for the Japanese version of Kingdom Hearts III.