With TSW expanding in countries and 3rd party creators being a thing, odds are eventually it'll happen. But in this case, for this suggestion, what route do you even want?
The line between Děčín and Dresden. It would be another cross-border route. https://forums.dovetailgames.com/threads/děčín–dresden-neustadt-railway.71025/
Really correct and by the way freight trains do not end at Dresden Neustadt but at Rangierbahnhof Dresden Friedrichstadt
would love it so I can finally learn MIREL and other safety and signalling stuff ... anyways, this is not Czech, but Slovak suggestion, but safety and signalling is shared I believe, so why not share the suggestion here: https://forums.dovetailgames.com/threads/western-slovakia-triangle-bratislava-trnava-galanta.85935/ that route would offer variety, interesting/nice scenery (especially Bratislava - Trnava line with the vineyards), nice modern rolling stock and great session length (a single run on any of the three lines would take AT MOST one hour with passenger trains, even taking into account possible delays )
