Thank you for introducing a new English terms (such as “baloon loop”) to me. It would be very satisfying, if a game named “Train Fever” use so many railroad-related elements. May be even borrow things like train water and maintenance in very simplistic way from Railroad Tycoon 3.
A problem of floating vehicles can be “fixed”, if you add many intersections or crossings along “flying” or “sinking” autobahn, but that’s not actually a fix, just a far-fetched workaround in-game (if I understand you right, though I am not sure).
If TF enabled decoupling, it would ruin an official “20-minute” rule 🙂 And I think an automatic station manager would became even much more needed, with cargo category classification instead of cargo type. (At least, may be simple like in Simutrans).