I think it would be a good idea if we had DLC packs that branched off maps such as London-brighton with dlc with routes that will connect with previous used dlc I think this would make the game play a lot more immersive and give a great experience for the player as a lot of the maps have linear lately (great maps however) If London - Brighton & east coast away were merged that'd be incredible as an example Or London Brighton line with the south London network DLC I think this would make player's buy and play train simulator a lot more As a personal suggestion London to Bedford with the use of the Brighton line with Thameslink would be great with a cheeky branch to east Grinstead and using Orpington/Sevenoaks route for Thameslink experience to Victoria yes I'd pay full price for a game this lol
We'd need the lewes-Plumpton (as it connects the ECW to the LBN) but other then that it'd be a nice touch to merge these routes. The SLN isn't a TSW route yet so that's not possible but I presume you mean something like Dannies south london ti brighton? And "thameslink service to victoria"? Maybe it's just worded poorly but thameslink don't go to Victoria, they go on TL core after east Croydon.
There are so many branches so far not represented on various routes and in many cases, it is unlikely we will ever see them included. The added gameplay options are many and various. A few examples are... Wivelsfield to Lewes (LBN & ECW) Old Oak Common to Northolt (GWE) West Ealing to Greenford (GWE) Southall to Brentford (GWE) Heathrow Airport (GWE) West Drayton to Colnbrook (GWE) Slough to Windsor (GWE) Maidenhead to Bourne End/Marlow (GWE) Twyford to Henley on Thames (GWE) Reading to Basingstoke (GWE) These are some of my personal favourites. I would happily pay £5-10 each to be able to play these branches as well as some older versions such as... Southall to Brentford Docks (pre 1939) West Drayton to Uxbridge and Staines West (pre 1962) Slough to Windsor (pre 1965) Maidenhead to High Wycombe (pre 1970) Twyford to Henley on Thames (pre 1965) All of these versions go to destinations not possible today due to closures or to much larger destination stations than today.
Route extensions aren't really a thing (SEHS was more of a rebuild than an extension) so if we're ever going to see an extension to BML/ECW it would likely come as part of a route upgrade replacing the original rather than adding extra track onto the original.
If the services don't traverse over both parts of the route like some of the Thames branches it would make more sense as a standalone route. Something like the East Grinstead branch for BML like the OP mentions doesn't make sense as a standalone route as you wouldn't be able to drive all the way to London Victoria.
Services like the one you mentioned would be able to be run as 2 parts until a better solution can be implemented. This is far from ideal but the only currently feasible option. I have thought about the Sheerness branch being added to the above list, another I'd be happy to pay for.
Sorry about that, yes I didn't really explain it properly I must correct my self. What I mean is if we paid __$/£'s for extra lines on previous DLC such as going to east Grinstead and I'm unaware of the publishing rights ownership stuff with add-on's so I apologize but I think it would be a very good idea to get branch lines layered into previous DLC such as the London Brighton line And yes we are missing Plumpton but and cooksbridge I think I can't remember but even changing for a train at Brighton with no load screen would be great oh a quick 5/10 load screen when going on to branch lines sorry my grammar is terrible but I think it would be great if we could almost get extensions but layered in game
