First? Punctuation. There isn’t any in this sentence in this edition. Which is interesting after the abundance of instructive punctuation in that first line of this speech in the same text. If you read this line without any commas, it sort of bounds right through and maybe it should. Maybe the regularity of the verse suggests no pausing until “give us pause.” It’s an interesting choice. I feel like some commas might help for meaning but maybe they don’t help for performance in the end. Maybe it’s tried and tested like this.
I’m hamstrung with meaning on this one, too. The line is so rich, so compact and so woven into our culture, I find I can’t sink my head into it directly. Shuffling off this mortal coil? It is a fucking punch you in the face extraordinary metaphor for death. That’s why people use it all the time, why this bit has stuck in the common parlance.
And you have to wonder – where did it start?
How did the good old W.S. come up with this particular metaphor. Is there a concept that it springs from? (See what I did there, coil, spring. . .yeah.) So there’s that. Shuffled off this mortal coil sounding a bit like shuffling off to Buffalo, which might, for some, serve as just as apt a metaphor.
“What dreams may come”? They liked that one so much they made a move with that title. (Was it any good? Did anyone see it? I just remember the poster.)
It all must give us pause really.
For in ·that sleep ·of death, (ABABAB)
What dreams ·may come ·when weee (AB ABAB)
Have sha·ffled off ·this mor·tal coil, (ABAB ABAB)
Must give·us pause. (ABAB)
I think the whole thing is one sentence. The upper casing on the subsequent new lines is just my preferences. I added in the two commas because you asked. The last line is indented to the right to indicate that it is more musically similar to “this mortal coil” than to “have shuffled off”.
About the meaning, I just winged it, so here goes: Sleep of death is Hamlet’s option A. Dreams are the benefits that he will enjoy by following orders. Mortal coil is his righteous principles. Must give us pause means to think deeply about the implication of getting benefits by sacrificing our principles.