Hello  @TP-Link ,

There is no discussion to have and this was the conclusion of my review video I published on Youtube (products sent by tp-link ...)

You HAVE TO provide WPA3 on AC devices, including M9 kits. And this is not the only feature you have to provide (or backport, as you prefer).

If you do not provide such feature, it means that the whole concept of Deco is falling apart: you cannot mix your Deco products, as the old one are not maintained and do not get the features of the new ones. Moreover you cannot find a map of the different features that all Deco have in common, and understand what is activated where and what will happen when you start mixing them. 

The new ones (X90) already are missing features compared to the competition, so this adds to what is not available in M9 and you have a network that lacks so many things that even a chinese crap is sometimes doing better.

If you want to keep Deco line-up as an high-end network product line, there is no need to think twice. Or you development team is busy, not setup to maintain existing products and provide new features and you have to hire or find ways to be more efficient, or Deco will start to fall apart and get very bad product review, as it is now the case.  

There could be technical reason not to deploy a feature, like higher CPU usage, memory consumption, ... but all Deco products should be aligned on their features and only the one that cannot run them should be deactivated with a log mentioning it. So that people buying them and mixing them know what to expect.

  @TP-Link any news here? I have 2 M9 Plus decos and I need to decide if I will buy two more, or sell it and buy something else with better support. There were promises that WPA3 will be supported.

  @aldiaz I don't think the question is when, but if.
Even on the higher end Deco X90 I have seen no update at all over the past year and more. This is the top of the line, the best of the best they can offer, and this product is in maintenance when you consider the huge amount of features it is missing compared to the competition.
So when you ask for a legitimate software upgrade to make M9 Plus still viable among the tp-link ecosystem, as it can work with other devices creating a WPA3 secured Wi-Fi, I guess there is no chance. 

To my understanding and if upgrading your coverage is important, I would consider the second option rather than expecting the unexpected !