Today Meizu released their weekly updates, featuring suprsingly a stable version of Flyme 4 (18.104.22.168A), for the MX2 and MX3.
It should be kept in mind that the MX2 got released 2012 and the MX3 in 2013, which means a continious support of more than 2 years.
We are very interested to know how long Meizu will keep both devices up to date and if they will get, the last year released, Android 5.0 (Codename Lollipop).
However, due to the technical specs, a release seems at least for the MX3 very likely and could be rolled out in the next few following months.
m1 and MX4 owners can be assured that Android 5.0 is coming within this year as well. Probably even before the MX3 gets it.