Not sure I understand the question. ARC is currently available on the Sonos Beam and the Sonos Arc. The Arc also is capable of eARC. 

The Sonos website says it will be February 5th before they'll start shipping the Arc.

Ah, you’re asking about the Arc, not ARC, gotcha. I would have to assume the data presented on the website is the best data currently available. I’m sure Sonos is doing all they can to get more inventory ASAP, but aren’t able to commit to anything yet. You’d likely see that date change in the order page as soon as they have concrete data. 

Thanks