If they do develop one last generation of ICEs for the future, the logical next step will be standardized displacement inline series from 3 to 6 cylinders. I think packaging efficiency is no longer a valid argument for the V6 because almost no new transverse FWD car is produced with V6 in the near future. Toyota was very stupid to develop the V35 to be as compact as possible but then not use that compactness to its advantage, in typical Toyota fashion.
We should be prepared to be disappointed by the Crown sedan because it will very likely be a simple S220 refresh.