Page 227 - Practical English Usage 3ed - Michael Swan, Oxford

6 obligation: shall
In contracts and other legal documents, shall is often used with third-person subjects to refer to obligations and duties.
The hirer shall be responsible for maintenance of the vehicle.
In nonnal usage, we prefer will, must or should to express ideas of this kind.
219 future (9): future perfect (they will have finished)
will have + past participle
We can use the future perfect to say that something will be finished or complete by a certain time in the future.
The builders say they will have finished the roof by Tuesday. I'll have spent all my holiday money by the end of the week.
Shall can be used instead of will after I and we (see 212.1). I shall have spent ...
A progressive fonn can be used to talk about a continuous activity.
I'll have been teaching for twenty years this summer.
For will have . .. used to express certainty about the past (e.g. It's no lISe phoning - he'll have left
by now), see 218.5,629.
220 future (10): future progressive shall/will + be + .. .ing
1 events in progress in the future
We can use the future progressive to say that something will be in progress (going on) at a particular moment in the future.
This time tomorrow I'll be lying on the beach. Good luck with the exam. We'll be thinking ofyou.
2 events that are fixed or expected to happen
The future progressive is also used (without a progressive meaning) to refer to future events which are fixed or decided, or which are expected to happen in the nonnal course of events.
Professor Baxter will be giving another lecture on Roman glass-making at the same time next week.
I'll be seeing you one of these days, I expect.
3 no idea of making decisions
The future progressive is useful if we want to show that we are not talking about making decisions, but about things that will happen 'anyway'.
Shall I pick up the laundry for you?,.., Oh, no, don't make a special journey.
,.., It's OK. I'll be going to the shops anyway.
..
future (10): future progressive 220
page 195