Although normally the dotted mesh grille should only be coming on the M Performance version(s) (M440i, M440d?), it might well come as standard across the whole range (bar the M4, likely), simply because the grille is just so large and might possibly look awkward with vertical slats. All prototypes that have been snapped so far seem to be wearing the mesh grille (except, again, the M4 prototypes which have horizontal M type double slats).
The new Z4 does come with the mesh grille even on the non-M Performance, non-M Sport, 20i version.
Yes, BMW has just launched huge grilles with vertical slats as well (LCI 7er, X7, X5 to an extent...), but those are status symbol models and/or SUVs and might well require the traditional chrome vertical slat design. The new coupés with large grilles though (4er, likely next 2er) might be getting a standard mesh grille across the board for a sportier look as standard.