The traditional rule is that shall is used with first person pronouns (i.e. I and we) to form the future tense, while will is used with second and third person forms (i.e. you, he, she, it, they). For example:
However, when it comes to expressing a strong determination to do something, the roles are reversed: will is used with the first person, and shall with the second and third. For example:
In
practice, though, the two words are used more or less interchangeably,
and this is now an acceptable part of standard British and American
English; however, the word shall is now seldom used in any normal
context in American English.
sursa: oxforddictionairies.com
I shall be late.
They will not have enough food.
I will not tolerate such behaviour.
You shall go to the ball!
sursa: oxforddictionairies.com