I always thought that HEVC was a hardware thing and wold never see this on rpi3, but now is like there's a light in the end of the tunel.
They're letting us dream kkkkk
In general HEVC is a hardware thing (or you need a very powerful CPU).
In the past RPi devs invested an enormous amount time to get HEVC playback working on RPi3 by offloading several CPU intensive tasks to the GPU - with really good results.
The problem is that this approach only works with the legacy proprietary graphics driver which has now been phased out.
With the new graphics drivers all of that old, optimized code can't be used anymore and adapting it to the new driver would both be very tricky and time consuming - and it's not even clear yet if it would be doable at all or achieve the same performance as with the old drivers in LE 9.2.
So: don't hold your breath, ATM we can't promise RPi3 will get back optimized HEVC decoding in LE 10/11/... any time soon.
so long,
Hias