The next Fireside Chat is today, we may get some information today. I remember back in October, Stewart and Welch were talking about Welch's first project being the Spring 2019 product and were teasing an announcement for November's Fireside. Since Welch was on vacation during that time, it was being pushed to maybe today. It was also mentioned that the Summer stream would be announced before the end of this year in order to give people time to make travel arrangements if they wanted to show up.
As always though, plans may have changed. I will give it a definite maybe that some news could be dropped today.
Now, as far as what those products could be...I think we're due another Xanathar type book, but I don't know if they have the content ready. I don't think we're getting another monster book yet either. My guess would be the "campaign setting" in Spring, the planar adventure in Fall (probably a version of the Great Modron March), and the November book could be that Xanathar style book with at least 8 months of playtest time. For the campaign setting, it could be as simple as another PDF release. I would hazard a guess that Wayfinder's Guide could be finalized by Spring...but we haven't seen the next iteration of the artificer yet.