If you look at the graph, you will see „two-hourly services“, sometimes coming from Vienna, via Villach towards Slovenia, and while I don’t think that these will really be two-hourly, there is a high likelihood that Vienna - Ljubljana will run via Villach in the future.
As regards Zagreb, indeed the plan doesn’t include anything definitive except an Interregio service from Graz to Slovenia, but it doesn’t exclude isolated services from Vienna on a commercial basis. As I have mentioned in another thread, unfortunately, demand is very limited and unlikely to change much due to the very slow nature of these services and the geographic detour they incur, whereas the motorway runs straight down to Zagreb.