Verbal | Real wages next year are forecast to fall more rapidly than they have

The following is an excerpt from TheEconomist:
Real wages next year are forecast to fall more rapidly than they have indecades.


What is the structure: to be + noun +to ?
"next year" is marker of the future tens, whereas the sentence utilizes the present tense "are".
I would agree, if the sentence employed the structure: "are + going to" for the future time.

Concerning the ellipsis, what the verb "have" substitute for?
Real wages next year are forecast
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