They said Alpha is Spring and we had first vendor 11.0 build already. Overall sounds predictable, after they confirmed 3 patches between 10.2 and 11.0, keeping tight schedule and release in Fall, add 2+2 and late September/early October is most obvious time to release.
And looks like S4 launch is independent from patch (although there is no info what 2.6 will contain beside S4 stuff), so most likely we can expect something every 2 month - 2.5 in January, 2.6 in March (+Alpha), S4 May, 2.7 July, 11.0 September (pre-patch).
Nice idea, it make sense. Would be perfect S3 catch up similar to Forbidden Reach.