I don't see any real change in the next 20 years. Civilian use of AR's won't be impacted by this (potential) gradual transition, and if at that point the round is in mass production for the military, it will also be pretty cheap (meaning: the little piece of steel at the end of the brass case won't add much more than 10 percent vs. a 5.56 round to produce/sell). The True Velocity kind of stuff would have been more disruptive, I believe (and still could be, ultimately).
The round would then be adapted/used in other platforms, and the initial patents/exclusivity given to Sig would expire for much of it (17 or 20 year timeframes).
Really though, the 300AAC is a pertinent correlary. For home protection/defense (among other uses/applications), it is in many respects superior, if pricier today, over the past 5 or 10 years. But, it has…less than 10 percent I think of civilian sales compared to 223/5.56.
Ubiquity is a virtue/value all to itself. The market will shift of course if…having a 'cool military-looking AR at a high dollar value' loses it's chic to a certain crowd, but that is not…the bulk of AR sales.