So, if I could be wild and crazy I would wish for long routes such as Koblenz - Trier, Hamburg - Hannover/Lehrte etc.
But, to be a bit realistic: Updates for the current routes to TSW4 standard, upgraded sounds for several trains (Such as the Bombardier Dostos), extension for Dresden - Riesa up to Leipzig, new trains such as the Desiro ML (for Vorarlberg and for coming Austrian routes) or the Coradia Continental (Br 1440, for Dresden - Chemnitz).
Another neat thing would be a way to generate your own buchfahtplans within the game, to make it more realistic driving without the HUD.
Time to wake up now, I guess, and stop dreaming so much…