Well, I won't argue about the depth of lines, because Sideshow has done far better than HT in that sense, but I don't think the price difference is so extreme as to turn folks off. If you are willing to pay $110-20 for a figure, you are probably willing to pay $160-70.
But at the end of the day, this would be a business decision. If Sideshow completely turns away from 1/6 scale figures, it is because they don't think they can turn a profit with it. However, like I said, I think Sideshow is doing pretty well with these two lines, or they wouldn't have lasted as long as they have with the kinds of releases we are getting. If the Joe line was floundering, I don't think they would do Red Ninja in lieu of someone more recognizable--that is a sign, to me, that they anticipate the line will go on for awhile.