According to the official Sony Xperia Twitter account, the Android Lollipop update is going to be available "only" for the Xperia Z family. This means that smartphones from 2014 like the Xperia E3, Xperia M2 Aqua (pictured on the left), Xperia M2, Xperia C3, Xperia T3, Xperia T2 Ultra, or Xperia E1 will not see updates beyond Android KitKat.
Hopefully, Sony will change its mind in regards to at least some of its recent non-Xperia Z devices (which, from a technical point of view, are certainly capable of running Lollipop).
As for the non-Xperia Z handsets introduced this year by Sony, the M4 Aqua is running Android Lollipop out of the box, while the E4 and E4g will get the update sometime after launch.
source: Twitter (1), (2), (3) via Xperia Blog