Will there be equipment for mounting units like L009 and RB5009 in 10 inch racks?
They can already be mounted
From that thread:
Is there another mounting kit?
As indicated in that referenced thread, no.
Adjust the rack or the K79 brackets.
Q: why 10" rack ?
I only use 19" material for that compatibility reason. Pretty standard and a lot easier to find.
10" are small and visually do not overhelm small rooms or could be flush-mounted ones (19" usually do not fit in such situations 
)
IMO that's not possible. RB5009 width is 220mm. And according to @inra , K79 adds 5mm (twice the thickness of those ears) ... and that has to fit inside the 10" rack vertical rails (which are spaced at 222.25mm).
So one would either have to make those rack ears thinner (and risk structural integrity), including head height of screws (which have to fit flush with K79 rack ears).
Or make space between rack vertical rails wider by 2.75mm (as mentioned by @inra ). Which IMO is much easier than playing with K79 rack ears.
I love listening to music in my tiny household and thus use network gear without fans, mainly because I don't have a nook to soundproof the units in. The very compact RB5009 currently holds the job of main router blinking calmly on a shelf under a 34 inch display that (along with a passively cooled computer) replaces a conventional TV here. The router might be combined with a similarly sized switch (eagerly anticipating the S009) in the near future. A small ARM-based server and a class-D amplifier in the same form factor are also in the pipeline.
So a small rack would be handy.
I was merely suggesting ...
If there is one thing I try to avoid, that's wasting time for things which are incompatible with all consequences that come with it.
I have a 19" frame mounted upside down under my desk (holding L009, used as managed switch and platform with mini-PC on it).
I have another 19" frame mounted vertically in a cabinet where my ISP router is (holding RB5009, CSS318 and power plug rail).
Everything out of my sight yet reachable when needed.
It should be pretty easy do design and 3d print brackets for it...
I have not got my RB5009 or my L00r into their 10 inch racks yet, so I have just taken measurements. The L009looks like just over 222mm and the space between my vertical rails is just under 221.
I think I might be able to increase the space between the rails by the required amount by putting the edge of the cabinet in the vice to sharpen the bends where the rail is formed from folds in the edge of the case.
They came up with everything before we did
https://www.printables.com/model/1236191-mikrotik-rb5009-10-inch-rack-mount
Sometimes you have to relax own rules when it's needed to manage tiny space and stuff all stuff in a shallow box eg. behind the curtain or in a corridor avoiding geting a tumor by taller ones
Well... Personally I would be happy with a scaled version of the SolidRack 10 rack. ...and mounting the rack hanging upside down was a really good idea.
That said... The 10 inch format seems to be increasingly popular. That's why I'm hoping for brackets as the primary option.
The 3D-printed brackets might be a solution and I'll look into using them.
A 10" shelf would also be an option, since it fits width wise.
There are lots of 10" rack offers for audio devices that could be easily installed "upside-down" eg. 
Once upon a time the Ikea Lack was a thing for replacing 19" racks.
Meet the Ikea Eket for replacing 10":
It fits, I just left the silver screws on the side rails a bit loose, fitted the 5009 with its rack ears into the rack, it's a tight fit, and then just tighten the rails. There's just enough slack.
This is my DC powered and silent homelab rack, Gigabit internet ONT, 48TB SSD NAS, no fans and draws around 60W.
Nice !
That's an Ecoflow with supplementary battery I see below ? Delta 3+ ?