When is McDonald's finally going to go out of business?

They will Never go out of business as long as kids love them nuggets and parents can go to them for a quick meal 

When the rapture happens.

When Wendy's, Burger King, Wimpy, Moss Burger and all the other franchises gang together, call themselves Empire Burger, form a Stormtrooper army and take over most of the western world. They will build a giant flying hamburger death star and launch a devastating attack on McDonalds HQ. Then the arches will fall and we will dance on the grave of Ronald McD.  However, Empire Burger will then raise their prices to extortionate levels and make it mandatory for everyone to eat their crappy facist junk food on a daily basis on pain of death if we dont. So, be careful what you wish for.  

when the cow jumps over the moon!!!

Mcdonald will remain to be one of the biggest fast-food vendors in the world.  

Hold your breath and wait.

Date is Feb 31, 2020

Most likely, never or in a very long time, since they're a VERY popular fast food chain. Also, this question is phrased negatively, do you want them to? Why?

They won't be going out of business anytime soon.

On the 35th of Neverember.