The phone's ringing. I'll answer it./ What are you doing ...

Hello.

I have read in an english grammar that:

"We use will for instant decisions about the immediate future:

What are you doing after the lesson? "

and that

"The present progressive is most used for arrangements in the near future, usually when time and place have already been decided:

What are you doing after the lesson?

I'm meeting Ronnie for a coffee. "

But if we are talking about the distant or far future, what tense do we use instead of "going to"?

And if we are talking about arrangements in the distant or far future, what tense do we use instead of "the present progressive"?

Thanks.