You can find the info about the 3 routes included in RH here. I guess each of us will have their own opinion about which route is interesting or not. The release date is Summer 2021 (there is no specific day yet).
That hasn't been finalised, though. This was mentioned in the Cathcart stream and as I understand it they're still deciding how it's going to ship.
It will definitely be offered as a bundle for $29.99 USD. As that is the standard price of one route, I'm not sure I understand why anyone would wish to purchase the routes separately? It seems like providing the option would just cause needless complexity for DTG.
Well if you're interested in only one of the routes, why clog your hard drive with routes you're never going to play?
If you're on PC, I think you can purchase the bundle and then delete any routes you don't immediately want. If you change your mind later, you can then redownload them from your Steam library. That way, they don't remain on your local drive.
We asked for this, but DTG said they still don't know exactly how it is going to ship. The only sure thing is that they are gonna sell them together at the price that is in the Q&A and not as separate purchases.
It is decided how they are going to sell it. What is not decided is if there will be 3 packages that you can install / uninstall (in case you are not going to use some of the routes and you want to save the disk space).
When they're released it will (most likely) be as a bundle, because that's what DTG have done every year On PC you can definitely remove individual DLC from steam I am not sure why Sam was ambiguous on how it's going to ship when this has been touted as "the summer release" since it's announcement, and their "summer release" is always three routes (and accompanying train assets) for the same price (as quoted above)
Sam was talking about if it is going to be a package that installs all (so you install all routes or none) or if it is going to be a meta-package that contains 3 packages (so you could choose to install 1, 2 or the 3 routes). In any case you would always buy the 3 routes, it is just a matter of your install / uninstall options.