I was thinking recently about how longer routes could be added into the game , obviously I'll preface this by saying I am literally thinking out loud here but would people be happy if we got a route from London to Edinburgh for example, and have it broken down into a number of different separate sections? This could be done by offering maybe 50 miles of route at a time and either loading in the next section at a certain point or having a DLC that's broke into a number of parts. I am presuming the reason routes are cut short a lot is down to development time and costs + limitations on consoles so maybe if this was something people would be interested in DTG or another third party could look into something like this? As I said earlier I'm just spitballing an idea here but is it something players would be interested in?
Matt has already explained why this would be a bad idea, if the routes arent actually connected and have loading screens in the middle the timetable wont line up. if you arrive late and then it loads the next one you will suddenly be on time again for example. There are alot of other problems why this wouldnt practically work. Extensions like the LIRR or SEHS is your best bet at actually adding more mileage
I dont think that would work for the ECML. Because they did Peterborough to Doncaster the rest of the line north would be weird, Doncaster - Darlington, Darlington - Berwick, Berwick - Edinburgh instead of the logical, Peterborough - York, York- Newcastle, Newcastle - Edinburgh
Extensions are the best way but you come across the issue of rebuying the same dlc several times since extensions can't work without each other. I think having like at least 1-2 extensions to a route would be a good idea since it would result in a longer journey, a more complete run and more variety without having to back out into the menu each time. This also allows for some variety in rolling stock so you have different sections focusing on different eras.