OMXPlayer supports ALSA for some time now [omxplayer -o alsa yourvideofile] but it hasn't been implemented on LibreELEC yet.
I agree that MMAL works fine, but using OMXPlayer still has its advantage. CPU usage will decrease so your RPi3 has spare cycles to compute other things.Will this be implemented in the future?
No
On the rpi kodi uses an RPI specific audio sink device so alsa isn't even needed at all.
So you're saying that you're able to use OMXPlayer with a HiFiBerry HAT (or clone) installed without the need of ALSA? You would be the first to accomplish that.
No I'm not saying that. You didn't specify the use of a hat 
for a hat you have to load the dtoverlay which auto loads the required alsa modules.
You're the first user that I ever encountered in all my OE/LE days who plays video's via omxplayer commands. It's not required for our user audience and thus we are not planning to re-engineer Kodi audio support to accommodate alsa in the OS. Kodi development has also been focussed on MMAL for some time now - OMXPlayer is in sustaining/maintenance mode only to continue basic Kodi support for the dwindling number of first generation devices and even smaller group of people who want to run Kodi on a pi zero. Sorry.. but no.
Thanks for your reply! However, there's one thing I don't understand. You said "we are not planning to re-engineer Kodi audio support to accommodate alsa in the OS", but haven't you already? To my knowledge (which may be flawed) LibreELEC uses ALSA to interface with the HiFiBerry HAT's. The latest binary of OMXPlayer supports ALSA as well, so wouldn't this be an easy fix or am I missing something here?
I'm not calling videos through the command line (at least not on LibreELEC), it was just an example on which parameter you should use to get OMXPlayer talking to ALSA.
The main reason I opened this thread is because I didn't (and still don't) understand the move from OMXPlayer to MMAL. When using Kodi on Raspbian with the latest OMXPlayer installed (with ALSA suppport) I noticed far less strain on the CPU cores than when using MMAL in the same environment. Besides, all RPi's share the same GPU so what's the advantage of moving to MMAL?
Please help me understand 
Uhh we don't ship OMXplayer on the base system. So I'm not sure what you are talking about.
The OMXplayer support in kodi is built into kodi, there is nothing to update there.
Unless I'm missing something....
