Sitelinks have certainly increased – and an important change in this regard is that that site subsections are now regularly producing sitelinks (that is, sitelinks are appearing areas of a specific domain or subdomain, rather than only for a top-level domain-focused query, or results relevant to a subdomain – try out “new york times sports” to see what I mean).

Interestingly – as per most of your examples – such a stack of results from the same domain tend to be in response to entity-related queries (which, in the context of companies on the web, can also be loosely classified as “brand queries”). Entity-focused results seem to be the area Google is tinkering most with these days, and as you note, they haven’t quite nailed it yet.

Given that such type of queries will continue to be a focus for Google, I wouldn’t be surprised if we see a return to something like indented queries, though in a different visual form. That is, a user interface that groups domain-specific results for such queries, but for results in addition to those which currently generate sitelinks for the first result.