As you know, Google deprecated their old AJAX crawling scheme proposal just about two years ago. But currently they still do crawl and index content from those pages. But Google's John Mueller said in a webmaster hangout yesterday that soon enough Google may stop crawling and indexing that altogether.
John said "I would expect that at some point we would be turning off crawling of the escape fragment URLs and we would only try to crawl crawl and render the the hashbang urls themselves." When this will happen is not 100% clear but those who are using escape fragment URLs should consider switching, if they have not done so already.
Here is the video embed where he said this at the 17:28 mark into the video:
Here is the transcript:
The other part that I'm a little bit more worried about is it sounds like you're using the AJAX crawling setup with the escape fragment URLs. And from our point of view that's kind of a deprecated set up.I would expect that at some point we would be turning off crawling of the escape fragment URLs and we would only try to crawl crawl and render the the hashbang urls themselves, which are kind of these these JavaScript pages.
So if you're only serving the structured data on the escape fragment version of the page then I suspect that will kind of make things a bit more complicated in your specific setup. So that's one thing I kind of keep in mind that that can happen at some point. I believe we stopped recommending the AJAX crawling setup maybe two years ago. So that's something where I expect us at some point to switch to the the rendered version.
Forum discussion at Google+.