I really hope that some <TSW4 content also gets the new rain effect. For example the BR103, ICE3 and Class 700 gets the new rain effects. Because the windscreen is very big and/or you sit very close to it. I would really enjoy driving in the rain with the new effects.
We just need TOD4 on all content, and all upgrades, mabye that'll come to TSW5, who knows? It'll just be a lot better for all of us. No more lighting issues, low res rain, 2D clouds, thin overhead lines, yeah that stays a dream.
It's a large job, as it needs to be modelled on each individual route - no plans at the moment to update pre-TSW4 routes. Agree though, we've seen some good feedback from players so far! On TOD4 - each route essentially needs to be redone for the shadows/tunnels to show (it's not as simple as ticking a check-box). Adding to Dresden was a significant undertaking.
Would love if it could become a goal to go back and improve like two routes a year to ToD4 or something. Maybe combined with a new loco DLC for the route like with Dresden. It's honestly pretty difficult to go back and play the older routes with how much better ToD4 is. Would really love to see Peninsular Corridor, and LGV Mediterranee: Marseille - Avignon updated to ToD4 eventually.