Sorry for the spoiler but no, Pro Tools 13 ain’t gonna happen. Or even 12.9. Avid recently changed the version numbering scheme to Year.Month.Bugfix. The latest Media Composer is already numbered 2018.1 and other Avid software will follow the new system soon.
If whole 4-digit (2018) year is not available in the OS, it will be cut down to the last 2 digits (18). Months with no software releases will be left out. For example, if the next Media Composer would be released in March (2018.3), there will be no MC 2018.2. If then March version gets a fast bug fix, it will be 2018.3.1.