Sonos hasn’t announced any plans to allow a 7.1.4 setup.

Your current 5.2.2 setup is able to play “real Dolby Atmos”.

A few months back, Sonos bought a company that was working on transmitting audio over BLE (bluetooth low energy).  From what I understand, that tech would allow an Arc or some other speaker to transmit audio channels to other speakers instead of using 5.0 Ghz WiFi as it currently does.  It could be that Sonos wants to use this tech to increase the number of speakers involved in their home theatre setup.

However, that does not mean that the Arc, Beam, Ray, or Amp have the required hardware to accomplish a 7.1.4 (or 7.2.4) setup via BLE.  It also is debatable, IMO anyway, whether there really is market for a 7.1.4  setup with a soundbar as the front end speakers.  I would think that if you want to have 4 surround sound speakers, and maybe 4 separate atmos speakers in the ceiling, than you would want to have separate front left, center, right speakers as well.  And you might not be all that concerned about wired/wireless speakers as well, and there is plenty of competition in that market.  So maybe the question is, does it makes sense for Sonos to develop a setup and products for more higher end wireless home theatre if there isn’t a big enough market to justify it?  I don’t know, but I wouldn’t be surprised if Sonos doesn’t go in that direction anytime soon.  I wouldn’t be too surprised if they do make something a few years from now either.

I want something like this and might even sell my arc to get something like the new Samsung 990b . Sonos has lagged behind the higher end soundbars that have 7.1.4 and one Samsung has 11.1.4 . Sure sonos has a robust following but with no innovation since the arc I’m losing interest 

If you’re after a “real Dolby Atmos” experience, I’d encourage you to not ever purchase a soundbar device, which by its very nature, restricts placement of some of the speakers. You’ll want something that has totally discrete speakers for all channels.