Tweet via @ image shows that Famitsu’s complete MGSV guide explains details on the nuclear disarmament within the games FOB mode.
Requirements for this to happen via JunkerHQ Tw
How to trigger the ‘Nuclear Abolition’ Event
This event can occur multiple times, provided all the requirements are met.
1. Complete Mission 31, Sahelanthropus
2. Don’t have any nukes in your possession or in development.
3. A certain requirement [related to nuclear proliferation – Piggyback guide] needs to be met on your game version’s server (PS3, PS4, Xbox 360, Xbox One, or Steam). They’re keeping this a secret.
4. After requirement 3 has been met, all nukes on your game version’s server (PS3, PS4, Xbox 360, Xbox One, or Steam) need to be decommissioned, bringing the total number down to 0.*
5. Complete a main mission or return to Mother Base.
*After requirement (4) has been met once, requirement (3) needs to be met again before (4) can be met again.
Now the likely hood of this happening is slim to none in our opinion but who knows. Until it happens (or doesn’t) you can always just watch the hidden cut scene on Youtube.