I don't know the exact answer but this is what i know from what i read here in forums .. They say that, the Group and Summon Points will remain and stay the same, then the other shops like Survival, Arena, Space-time will be automatically converted to Sun and Moon coins so, we have no choice to change it or not as it is automatically converted .. Some other people also says that the coins has some sort of cap or maximum capacity so other people ask what will happen if they have 100k+ points in shops ..