If it is said:

“What favors referring the pronoun to the final clause here is that this clause is joined to the preceding one by wāw (‘and’), and another clause is joined to it by wāw. This entails that it differs from the first clause regarding generation-by-generation succession. Here, the endowment is shared among the generations, so the only provision common to this clause and the first is that the endowment applies to them all; the manner of entitlement differs. This entails that the clause stands independently and that what follows it applies exclusively to it.

“For when clauses are separated by a condition attached to each, the final condition necessarily applies exclusively to the final clause. This is due solely to the differences in their provisions in that case, and such differences exist here.”

This may be answered in several ways.

First, your statement, “It is joined by wāw, and another clause is joined to it by wāw,” implies that the clause in question is the word “progeny.” If “progeny” and “posterity” have the same meaning, then nothing distinct in meaning has been conjoined to it. If they have two different meanings, the pronoun must refer to the clause being conjoined, not the clause to which it is conjoined.

Second, regarding your statement, “This entails that it differs from the first clause regarding succession,” we have already disputed this. We have explained that some jurists regard this endowment as passing from generation to generation until the Day of Resurrection. For the wording:

“Then for his grandchildren and his progeny and his posterity”

neither affirms nor negates succession. However, since the default is the absence of succession, we excluded it when the wording was unrestricted.