There is no general replacement of older plates - any dealer plate issued since 1992 can still be on the road or remade on this base.
Newly issued plates are on the flat base.  . No sequential issuance patterns have been spotted so far.
Reverse format new car dealer plates have been seen in the DFG series (same as with the previous base).
Courtesy dealer plates now have the car number in the upper right, like courtesy passenger plates.
Courtesy of Liberty Subaru