It has been eight months and one day since the last toolbar PageRank update and the one before that was on February 4th, a 10 month wait time. Prior to that, Google updated the toolbar PageRank every 3-4 months.
Do you think Google will do another toolbar PageRank update in the future? I bet they are trying to avoid it at all costs.
And the update they did in December 2013 was not really on purpose. Matt Cutts said then, "Team was fixing a different backend service and did a PR update along the way."
So will they update it in the future? Maybe, I mean, if all these sites switch to HTTPS, all the PR will be down to 0, so they might have to refresh it once in the future, to assign PageRank to those new URLs.
Personally, I wouldn't mind if they never updated it again.