5.55 indicating certainty

If you are sure that something will happen because arrangements have been made, you can use the future continuous tense.

• I'll be seeing them when I've finished with you.
• She'll be appearing tomorrow and Sunday at the Royal Festival Hall.
• I'll be waiting for you outside.
• Dear Professor Zapp, I gather you'll be using my room while you're here.
• They'll spoil our picnic. I'll be wondering all the time what's happening.
• Our people will be going to their country more.

Note that an adjunct of time or an adjunct of frequency is normally required with the future continuous tense.

5.56

If you are referring to something that has not happened yet but will happen before a particular time in the future, you can use the future perfect tense.

• By the time he is twenty a countryman will have killed a considerable number of animals.
• Maybe by the time we get to the dock he'll already have started.
• Maybe when you come up, you'll have heard from your sister.

Note that you must indicate the future time referred to by using an adjunct or another clause.