11 March 2015
According to the Google Operating System, that is when I will run out of gmail space - of course by then several of the development mailing lists I subscribe to will be only interesting from an historical perspective. The result does not make sense to me - since last April (when the space was increased to 2GB and the constant space increase started) I have used 400MB and the space has increased to 2.755GB, i.e. I keep storing email at a lower rate than space is added and so should never run out of space.
Update: It would appear that at some point the rate of gmail space increase dropped significantly.