Since March, we've been talking about how Google has been commenting that they will deprecate the AJAX crawl proposal. Well, that is still in the works.
John Mueller from Google said so in a Stack Exchange thread. Mueller wrote, "at some point we'll deprecate our recommendation to use the AJAX-crawling proposal."
He said this in response to someone saying that they shouldn't support it. He wrote:
Google has gotten really good at reading & processing JavaScript-based content for web-search. For the most part, if the files (JS, CSS, as well as any AJAX/JSON/JSONP responses) aren't blocked by robots.txt and can be crawled normally, we'll be able to render the pages like a browser would, and will use that for web-search. I suspect at some point we'll deprecate our recommendation to use the AJAX-crawling proposal (escaped-fragment/hash-bang-URLs), though we'll probably support crawling & indexing of that content for a longer time.
So even when Google finally decides to officially deprecate it, Google will still support it for some time after.
I am surprised it hasn't been done yet, but I guess they have other priorities.
Forum discussion at Stack Exchange.