It’s hard to tell if Google will add SERP summaries like the ones mentioned in the patent application, but it is something that they could do, and I imagine that the approach that they describe could provide some decent summaries of search results. I imagine that they might be struggling with the same questions – will providing summaries help searchers and help site owners.

I do like your answers to those questions, though I’m concerned that sites that show up in those search results that don’t fit into the more frequently appearing category that the summary suggests, but are still very relevant for the query, might end up being overlooked.