1.Niantic makes polls for Events and updates
Niantic could make polls for Events and updates.All Players would be able to vote.
The Second idea is PVP.Example how it could work:
Trainer 1:Venasaur,I choose you!
Trainer 2:Charizard,I choose you!
Trainer 1:Hold up,come back Venasaur!Blastiose,I choose you!
Trainer 2:Hold up,come back Charizard!Blastiose,I choose you!
And so on.
Pokéstop Submissions would be good for Rural Players to get more Pokéstops.
Breeding would be very fun.I have no idea how they will bring this in the game,but it would be cool.
5.Gym Lure Module
A Gym Lure Module would be very fun and an intresting item.As your waiting for someone to come to the raid,you can put on a Gym Lure Module.
6.A Pokémon GO Chat
A Pokémon GO Chat would be very fun and cool.
These are my ideas!