How does the final paragraph of the essay "A Modest Proposal" contribute to Swift's rhetorical purpose?

The final paragraph of Swift's "A Modest Proposal," first,
serves the usual purpose of a final paragraph in an essay by providing the conclusion. 
He summarizes the benefits of his proposal, for
instance:

• it's for the public
  good


• will advance
  trade


• will provide for
  infants


• will relieve the poor of their
  poverty


• will give some pleasure to the
  rich

Beyond that, the final paragraph
establishes that the speaker is not making this proposal so that he can profit
financially from it.  He has no children that are not already too old, and his wife is
past child-bearing age. 

In general, in addition to these
specifics, the paragraph contributes to the irony of the piece, as well as the humor. 
The speaker presents his proof that he is not trying to get rich off of his proposal as
if it is a serious proposal, continuing the irony used throughout the
piece.