While I understand that Neil and Geddy may have said this isn't the last, there was also something else that Neil said that is quite telling in it's suggestion that this will be the final Rush Studio album.
Neil has said that he intends Clockwork Angels to be his greatest achievement lyrically and drumming wise. That is quite a statement. He doesn't strike me as the kind of person who would say that album after album, and to my knowledge, he hasn't made this comment publicly before this.
So, if he intends Clockwork Angels to be his greatest achievement, what does he intend the next one to be, inferior? No, I don't think so.