@Tomislav Addai: Very interesting maps!
Also, I have two questions:
1. How much would Slovenia's lack of coastline have hurt it had it become independent without its post-World War II territorial gains (at Italy's expense--for instance, this could have happened had Italy remained neutral in World War II)?
2. Why didn't the SR borders in Yugoslavia follow ethnic lines?
The results of a landlocked Slovenia would be quite dependent on its relationship with its neighbours. The relations with Italy would be quite complicated, while if relations with the rest of Yugoslavia remain reasonable its implications could be eradicated.
If Slovenia remains outside of Yugoslavia I can imagine it remaining in Austria.
I cannot really imagine rump Slovenia existing on its own.
Why? Because Croatia would be disconnected Dalmatian would separated by Serbian part from rest of Croatia, while the western Slavonia panhandle would effectively separate Slavonia from Zagreb.
The most reasonable ethnic border was that drawn by Macek and Cvetkovic, which provides for ethnic and reasonable borders.
Titos policies were based on calming down nationalism, as Tito fought Ustashas and Chetniks in WW2.
Drawing a border across Bosnia is I think too big a challenge. (Yes , Herzegovina can be divided quite nicely, but not Bosnia)