Any (even distant) plans to finally add trains? In terms of mass shipping of goods and people, as well as being the most feasible eco-friendly mass transit solution likely to happen in game (planes and buses both being highly problematic for different reasons) it is such a natural fit. Plus you have a lot of different parts required for them, in addition to needing to plan for the tracks - so they add another area where both players and towns are encouraged to work together to provide something beneficial to the whole.
Not before release from Early Access - the latest survey we did was in favour of Animal Husbandry. We also don't think there is too much senseful use for trains in the constraints of Eco's worlds for them to deliver notably fresh content for players design-wise currently. They're definitely still on the plans, but currently even selling electricity did surpass it on the feedback tracker - so they are not in any active development.