There is no information shown on how long the Cyber Mystery Bag would remain in the game, but it would probably be removed after 1-2 days, starting today.
You can send the Cyber Mystery Bag from the Free Gifts page. There are also automated scripts out there which you can use to help send the bags, such as the Massive Sender(MWAddon) or Gift Blaster(Spockholm).
Here is the screenshot of what i received from opening 20 bags. I didn't receive much, but who can't reject free stat points?
Upon opening 20 bags for the day, the Cyber Mystery Bags will automatically be converted into the Blue Mystery Bags.
The Special Loot you can receive from the Cyber Mystery Bags is the Cyberpunk (175/129). It will randomly drop when opening the bags, along with other great stuffs such as the +5 Attack, Defense, Stamina, Energy, Skill Points and Stamina Boost.