Minimum requirement for a bag (IMO):
1 understable driver
1 stable driver that holds any line
1 overstable driver
1 midrange
1 roller
1 putter (though the midrange can be a good putter too, still I'd recommend a low glide putter)
That's a good list. I carry two different overstable drivers, one that is long range, and one that is a shorter more controlled drive. I also carry two midranges. I like having a stable and an overstable mid...the overstable one being for the shorter controlled upshots and the stable one for everything else.
I would just add those 2 categories to your list for a total of 8 molds.