Basic answer is: never
Devices are pretty rarely backported to already released stable release branches.
The new device will then be in the forthcoming 20.0x release, when it gets done later this year.
If some developer gets interested in the device and the needed changes are minimal, the support might be backported to 19.07, but that would be more like an exception that the default behaviour.
Easy amigo...
Thank you all. I updated my Linksys wrt3200acm and got everything back up and running normally in minutes.
Nice! My contribution made it to the release notes page 
Amazing work all around!
I think it should be re released with a newer bugless luci, one without the log out login issue
Upgraded my C7 V5 and my NBG6617.without a problem. Thank you.
btw when I can't log into LuCI after IP address changes I visit the logout page first.
http://192.168.1.1/cgi-bin/luci/admin/logout
No such problem with my C7 V5
Upgraded both Archer C7 V2 and Home Hub 5A form 19.07.2 to 19.07.3. All went smoothly. Looking good.
Thanks guys!
Flashed my Archer C7 V2 and it's been 24 hours with no issues on heavy usage.
I reported this on GiHub and has been fixed by @jow
See here for the details > https://github.com/openwrt/luci/issues/4093
There are a few bugs with the new firmware but I am reporting them. The quicker they get noticed the quicker than can get fixed.
LuCI SSL has definitely improved. Firefox mobile had problems working with OpenSSL and the LuCI web-GUI over HTTPS but it's now very smooth and no more page timeouts for me.
Hi
19.07.3 seems to be non-starter on my x86 box (the snapshot builds were the same too last time I tried them). Kernel log on console stops at "random: crng init done". The intel i211 nics don't get loaded so I'm limited to console to interact with it.
On 19.07.2 it's loading up the ethernet drivers at that point:
[ 5.607877] e1000: Intel(R) PRO/1000 Network Driver - version 7.3.21-k8-NAPI
[ 5.609598] e1000: Copyright (c) 1999-2006 Intel Corporation.
[ 5.611906] igb: Intel(R) Gigabit Ethernet Network Driver - version 5.4.0-k
[ 5.611929] urngd: v1.0.2 started.
[ 5.613536] igb: Copyright (c) 2007-2014 Intel Corporation.
[ 5.624497] random: crng init done
[ 5.848583] pps pps0: new PPS source ptp0
[ 5.850605] igb 0000:03:00.0: added PHC on eth0
[ 5.851939] igb 0000:03:00.0: Intel(R) Gigabit Ethernet Network Connection
At first I though the default build might have changed and it might be missing a kmod (although I checked e1000/e1000e & igb are there). I did a custom build with all the packages inc kmods from my 19.07.2 setup and flashed to a test partition but the problem's still there. No sign of life for the nics. So I'm not sure where to go next with it. Am I missing something (PEBKAC?)
Make sense to anyone? Any ideas would very appreciated.
Updated 5 Meraki MR24 AP's via GUI, keeping settings (and re-disabling dnsmasq, firewall, and odhcpd). No problems, and all running smoothly after two days. Many thanks!
Great work guys,keep up the good work!!
Any support for tp-link archer c3200 anytime soon?
If you own a C3200 and you would like to help to get OpenWrt on this device, please open a new topic.
Success report for WNDR3800 (really the WNDRMACV2) coming from 19.07.2 ath79.
Thank you OpenWRT Team for providing this build
My routers are working without any defects
Appreciate that 
Hello i'm up and running smoothly on 19.07.3 since 10 days.
Btw i've noticed strange messages on syslog, I dont know what they mean, like:
Tue Jun 2 11:12:23 2020 daemon.err dnsmasq[2226]: failed to send packet: Host is unreachable
Tue Jun 2 11:12:24 2020 daemon.err dnsmasq[2226]: failed to send packet: Host is unreachable
Same message repeated like 30 times... any help would be appreciated
Thanks
This is running phenomenal on my WRT32X. Only thing I changed was installing Linux kernel 5.4.42 off of the davidc502 mvebu builds. Bandwidth tests max out my cable modem with A+ quality and A+ bufferbloat ratings from dslreports.com/speedtest. Network sharing with samba4 is running 80-100MB/s off my USB 3.0 hard drive. 5GHz wifi is stable. SQM and Adblock work great, Luci is fast and silky smooth, everything seems in a good place right now. Thanks for the hard work everyone!