Definitely an Alex type of question (maybe he can drop by and share his thoughts
), but as far as I know while the
Roadmap isn't maintained at this time, the
Release Notes are kept up with the latest changes to the beta. It's not a glance at what 2.0 might be, but it does elude to the overall direction and show what is on the way. It's likely to be updated once 1.8 is released as some of the goals on it have been reached.
I haven't heard anything about 2.0, such as if it is intended to be a separate product (I dont think so?) which seems to be your concern here. At any rate, Playmaker 1.7.x is quite robust and 1.8 is added some needed features like Array management and a vast number of other improvements you can find on the Release Notes page.
1.8 Beta is currently well along in its beta (release candidate 17 iirc now) so I would expect it soon, however its hard to say since recent Unity 5 beta's seem to destabilize things sometimes it may be closer or parallel to when Unity 5.0 drops.
I hope that clarifies a bit.