I don't think he knew that prior to the first games release. That's what you're getting at, right? At least that's how I read it. It implies that Yu Suzuki planed beyond the release of the first game, wich he sure did but not in a way that he expected it to bomb and thus planed to let the second one end like it did.
Shenmue was his baby, he put so much time, effort and love into it. If you're giving that much of your life to a game like that I'd say you'll be absolutely sure that it will sell well. Yu Suzuki had a lot of experience in the market and since he did his best, he absolutely had the right to have faith in his work.
The decission of letting Shenmue II end on that cliffhanger was rather because the Dreamcast was already almost on it's last leg when they were in the middle of the developement of Shenmue II. I guess that it was originally intended to end at the end of disc 3, wich would go perfect with the ending of the first game. Then they decided to add the Guilin part very late in the process. It may seem strange to add more to the game in a desperate situation like that as one would assume it's the other way around and they actually cut off the game. But I think they all knew that there won't be a Shenmue III on Dreamcast and since Sega's future was unsure they knew there wont be a sequel in many years (and man were they right...)
I guess they added that part of the game for the players really. Like "Hey you're possibly have to wait a decade or more for III but at least here you finally have the meeting with Shenhua, the girl from Ryo's dream and that was on like every artwork and cover of the games." Maybe then they actually planned to spark a huge demand for Shenmue III among players with the massive cliffhanger. Interesting thoughts...