I'd be amazed if they dedicated much to guilin at all in the last episode. That whole disc 4 section is beautiful storytelling for a game but it's not a cliffhanger or ending on a bang which new fans need to be left with, nor is it a pacing that the anime has even attempted to this point. Personally, I'm glad they decided to bring the Lan Di rematch forward and I think it would be enough just to have Ryo and Shenhua meet at the end of the episode and that's it. Next season (if there is one) can deal with the issue of how much time to dedicate to it and to build their relationship, but it would be silly to try and fit it in now.
I also wonder if they would even want to do a season 2 before the release of S4 as considering how fast season 1 has gone through the series, season 2 would either have to stretch S3's events beyond recognition (and be very slow), include a lot of extra S3 story (which would likely bring up a lot of S3 story criticism again) or would have to include S4 events and ruin the story of an upcoming game.
It really would be perfect if the anime ends with a 'See you in Shenmue 4' message. That would be all kinds of epic, and almost most importantly, would be telling potential fans to get on Shenmue 3 in the time being.