Front Left and Right with Arc Ultra

The reason the other requests are ‘dead’ is they haven’t had any posts recently, closed by software processes, not by moderators. 

Sonos doesn’t lay out its roadmap. Possibly to keep features ‘protected’ from poaching by other companies, perhaps as writing new features is challenging to define in terms of timetables, other than with broad strokes. 

Frankly, this has been a request since Sonos originally released the PLAYBAR. I might guess there are technical reasons, or maybe not, but it does seem, given the amount of time the request has been extant, unlikely to occur. 

What you requesting is do able today based upon your wording to use the Five as additional Left/ Right for Hi-Fi audio. All you need do is set the Five’s up as a stereo pair and position one on the left and the other on the right and group with the Arc Ultra for Hi-Fi audio. 

However, seriously I doubt the above is what you are wanting. Hi-Fi audio is typically associated with Music and not movies. You are most likely wanting to use the Arc Ultra as Center channel and the Fives Left/Right channels as in a Home Theater setup.

I only bring this to your attention as wording is critical to properly convey your thoughts. If you want to use Fives on either side of the Arc Ultra for Hi-Fi audio (music) you can. However, you cannot use Fives as dedicated Left/Right channels and the Arc Ultra as a center channel which is associated with DD5.1 audio or higher and now Atmos. As ​@Airgetlam stated only Sonos knows if or when that might be possible and they aren’t talking about future designs.

Note: Even if you set the Fives up as a stereo pair flanking the Arc Ultra you be fine for music but not movies as there will be a 75ms delay.