Theoretically anything is possible. Google is constantly testing and changing their algorithm. They are constantly seeking out quality signals and it is possible they may be looking at this signal.
Realistically IMHO it is not a significant concern. There are many legitimate reasons to have low views per visitors. There are also many websites with low views per visitors that have ranked and continue to rank very well.
There are many online calculator site and online tools that rank very well. I have a few sites that offer free online tools. For these sites the average page views per visitor is less than 2 pages and the bounce rate is above 80%. I have been ranking in the top 3 for over 5 years and still rank there after Panda.
I am not advocating low views per visitor. I think most websites will benefit by adding quality, engaging content that attracts visitors and makes the website more "sticky". In certain situations low views per visitor is a positive sign. It means your page served the user. Sometimes users are looking for a quick answer so they can return to the real world and get offline.
I think you have a much bigger issue with ensuring that Google can easily crawl, index and categorize your content since you have switched over to AJAX. Also switching to AJAX can have significant impact on your internal link power.
Unless you are programming in a web framework that has Google's ajax crawling protocol built in, don't use it. Their "solution" is arcane and unmaintainable. You have to maintain two sets of urls on your site, one for ajax users and one for crawlers.
Its far simpler to keyword targeted landing pages at search engines and power deep content, filters, and search with ajax. Those are areas that you generally want to keep the crawlers out of anyway.
To your original question, I have a site that I try to give the user all the information they need on the landing page. My goal is 1 page per visit, but it is currently closer to 1.2 pages per visit. Hopefully, for my bottom line, after users get what they need, they click on an ad. Google loves the site and continues to send it tons of traffic. When Google says they look at "user experience", they clearly have a broader view of what is good for users than "view lots of pages on a site".