I would like to suggest that DTG spend time exploring ways to merge routes. Hopefully over time, we will see more routes that share connections. Currently, as far as UK routes are concerned, we have London Commuter which connects with East Coastway at Brighton but with no way of switching to each other without returning to the main menu. I hope a solution can eventually be found.
As long as we don't get concentrations of routes in a specific area just because they merge. Plenty of other regions to explore first.
I don't personally play the German routes and am not familiar but understand that there are connections.
DRA and DCZ can't be merged together, they are both set in different time. On the other hand, I think RRO and RSN could be merged (and I think theres already a mod).
This is something that hopefully happens in the future. The potential of this would be huge if dtg were to do something like this.
This, as of right now, there really isn't any US routes that can merge into each other, and if they did, they would most likely all be centered around the NEC. Which would pretty much ignore the rest of the country and eras.