I am sure a RE calendar would be as superb as any other RE production but I suspect the printed calendars generally have been hit by the use of electronic organisers. If there were new pictures, my wife and I might buy one but I doubt we would use it. It’s just too convenient to be able to check dates and diary anywhere any time.
A cousin of mine is a photographer and printer and for many years has produced a beautiful calendar of the hills, castles and other sights of the North East of England. While one does not discuss business in the family, I suspect sales are not flourishing. I grant he has not (yet) tried chained, naked slavegirls as foreground subjects, but I can not be sure the overall effect on sales would be positive.