The Samsung Galaxy A family will have an update to Android Lollipop, however the firmware for the Galaxy A3, Galaxy A5 and Galaxy A7 will be based on Android 5.0 Lollipop instead of 5.1 version. Once that Google recently announced Android 5.1 Lollipop (the next Lollipop revision with minor updates and fixes).
According to a source from Samsung, the company makes no plans with to update to the Lollipop 5.1, just yet because not all Lollipop ROms are ready to deploy. There is a chance of Google release Android 5.2 in a month or two, so it’s probably wise to wait some time.
Samsung previously announced it will release and update the Lollipop to the Galaxy Alpha early this year, but there is no further info on the matter.