While it's difficult to demonstrate a negative, after an exhaustive search through discussions at FlyerTalk and Milepoint, blog posts at The Cranky Flier and Boarding Area, and articles at other places which report on the vagaries of AAdvantage and its tools, I'm prepared to say that as of May 2015 the answer is still no, it is not possible for passengers to view the upgrade list for a flight from AA.com or anywhere else except the mobile app. The FlyerGuide AA upgrades page, last updated February 2013, is thus still accurate on this matter. I have an AA flight on Sunday; I'll check myself some time after T-4.
The list has been available for a while with American's competitors, and the inconsistency of having the list on the app but not the website has been brought up before, but only AA management would know for sure what the issues are. It could have been a business decision, it could be a technical or managerial barrier, it could be in development as we speak, but it's all just speculation on our part.
Indeed, even the AA mobile app is limited compared to competitor offerings, as the list is only visible from four hours before departure.