Anywhere beyond Klagenfurt, so Villach, Venice, Lienz...
I would expect a minimum 2tph as far as Graz, one running fast from Wiener Neustadt to Bruck or Graz. It would make sense to run Prague-Villach (but probably not Venice...).
There is actually quite a lot of information on the future ÖBB timetable, since this is a PSO operation and has to be made public (even though of course details may change).
Basically, these are the plans:
2 trains/hour south of Vienna.
- A „fast“ service, nonstop between Wien Meidling and Bruck/Mur (probably partly coming from the Czech Republic). South of Graz every second hour nonstop to Klagenfurt, then onwards to Villach and then Venice and/or Ljubljana. In the other hour, this service ends in Graz.
- an hourly „slow“ service to Graz and onwards to Villach serving intermediate stations, e.g. the two new intercity stations on the Koralmbahn. Every second hour this service will extend from Villach onwards to Salzburg (and mostly Munich).
Almost all other services in large parts of Austria will be reorganized and structured along these services, which will form the backbone of the „Takt“.
In the two years or so between the opening of the Koralmbahn and the Semmering tunnel, only part of this service will operate, since the tunnel is actually more important in increasing attractiveness of the service.
There might be open access services as well, of course.
