I think the 50+1 rule is a good idea but there are many potential negatives with it, the biggest drawback of the 50+1 rule is that it limits the financial capacity of the clubs. Without being able to captain the ship, external investors would not like to channel heavy funds into a team and current investors might decide to leave.
This will mean the major sources of PL club finances will be limited to the revenue generated through operational activities like match tickets, shirt sales, et al.
This is why Bayern is so dominant financially in the Bundesliga.
So I can see the big 6 doing 5 but the likes of Evertin, Leeds, West Ham may struggle to get potential investors.