I think the more relevant question Marc needs to ask from a market perspective is who and how many potential customers actually would purchase a Rigby, regardless of caliber, because it had no sights.
I frankly think this idea is either about ten to twenty years too late or perhaps five to ten too early depending the pace of suppressor acceptance in this country. Unless Rigby is also planning to stock it synthetically, cut the price by two-thirds, thread the barrel, and target a very different consumer segment. Hunting videos from Europe show quality rifles without sights equipped with suppressors. Franz Albrecht Oettingen Spielberg comes to mind. However, I can not think of a single person in my circle of acquaintances who would acquire a suppressor friendly Rigby, as currently configured, because it did not have sights.