I'd agree that it would be a good style choice to have [medium pause/break] ... [short pause/break] here. One way round this is to push the supercomma usage of the semicolon:
- They dance in the distance like graceful stage performers; their stage, the sky!
Hopefully, the rather poetic register will dissuade hyperprescriptivists from claiming foul. But here are several examples of the use of a comma to replace omitted words that goes beyond that of the usual gapping comma (standing in for words already used in the sentence: John likes strawberry ice cream; Sue, vanilla). Fragments are usually left:
- Not five blocks further, in the northern direction, a man stood on the corner, grimly silent, both hands in the pockets of his shabby top
coat, disappointment stamped on his countenance. His only plea, the
finding of a job. His was gone, but his family had to eat ....
[The Reflector; 1933]
- Tomorrow, the World! is a 1944 black-and-white film directed by Leslie Fenton ....
- But for Mark Standish, 'Run through the Jungle' has a totally different meaning as he literally runs through the Vietnam jungle to
get away from his decisions. His sole purpose, to destroy the one
person he sees as the root of all his bad decisions.
[Natalia Morrow]
- ... or the [Holy] Ghost ... will ... bid us turn
and flame unto a last consuming light:
His light, our light ....
[Scott Cairns, poet]
- Black Lives Matter ... You bleed, we bleed. You suffer, we suffer.
[Waves of Positivity]
And Wiktionary and Farlex Dictionary of Idioms accept
as having entered the lexicon.
The literary (or pseudo-literary in the last example?) flavour is seen in these examples.
One reference not confining the 'omitted words comma' to gapping is:
1.13 Consider using a comma where one or more words are omitted but understood in context.
- (a) Understood words. A comma pause signals the reader that an obvious word or phrase, commonly the verb from the previous clause, is
to be understood at this point.
[Redbook; Garner, I believe]
If you want to play it safe, signal a slightly more marked first pause with a dash:
- They dance in the distance like graceful stage performers – their stage, the sky!
(To my mind, the spaced en-dash common in the UK is less jarring. And the colon is becoming dated in running text.)
An ellipsis gives even more pause for reflection.