Whilst I realise this is quite broad international routes would be great on TSW in the future; here are some suggestions (feel free to comment and add more!): London to Paris/Brussels/Amsterdam - HS1, Channel Tunnel, LGV Nord, HSL 1, HSL 4, HSL Zuid Brussels to Aachen (link to Koln) - HSL 2 & 3 Munich to Bologna - Not sure of specific lines but would include the Brenner Pass Paris to Frankfurt - LGV Est
I would love to see the London to Paris Gaur du Nord. (Sorry if I spelt that wrong). It could be an extension for the new SEHS Extended for TSW3. SEHS Extended Extended. Lol. Or a whole other route.
You Forgot Duisburg (HRR) to the Netherlands Arnhem 99 km Utrecht 156km. Spoiler: HRR to the Netherlands extension THis requires the big Mulheim Styrum junction to be expanded to Oberhausen Hbf and then to Utrecht via Emmerich am Rhein voltage change point at Zevenaar for 1.5kv dc . Bundled and merged with HRR as Hollandstrecke Duisburg/Bochum-Utrecht Another one is Dresden Bad Schandau Decin (Bodenbach) Elbtalbahn. Can be sold as a bundle with Riesa-Dresden as the Saxon Switzerland adventure pack
You could then turn the whole thing into a massive Thalys expansion which is quite apt seeing as Eurostar and Thalys are merging.
Which one the Hollandstrecke Duisburg Utrecht or Elbtalbahn Dresden Bodenbach? Regarding Thalys it does not run on HDU merged with HRR the HDBU Spoiler: HDU HDBU full forms Hollandstrecke Duisburg Utrecht merged form Hollandstrecke Duisburg/Bochum-Utrecht instead these are the trains found on it DB BR406 and DB BR408 NS Dutch Railways 193 Sleeper train jobs DB BR1429 Tri voltage. Freight is DB BR189 193 and Dutch SNG ICNG VIRM. Thalys runs HRR SKA Paris Nord Dortmund Hbf via Duisburg and Aachen.
Couple of shortish ones Geneva RER has a lot of Cross Border working - and is jointly run by SNCF and SBB. Three Country Corner? Centovalli - Runs Switzerland to Italy - I believe the two companies on the line - SSiF and FART - are under common management. French Rivera line has a short excursion into Monaco (2nd shortest national railway in the world, and entirely underground) as well as a short section in Italy up to the SNCF/FS Boundary