http://www.sbs.com.au/news/article/2017/02/24/slater-set-miss-opening-nrl-rounds
Quote from Bellamy re: Munster
""Obviously Cameron has trained mostly in the halves in the pre-season so to put him back there would be a big call but having said that we've got to do what we think is best thing for the team.
"Hopefully by Monday or Tuesday we will know what we're doing and train from there.""
So no decision yet.
Personally I think it depends on Slater's prognosis. The less likely Slater is to play a role this season, the more you'd put Munster at fullback. If you have confidence in Slater to return, keep Munster at 6.