I believe that trains in the future will be a lot different than the trains we see today. Trains today run on electricity or diesel for the most part. In the future, they will find some eco-friendly way to power trains like perhaps solar or wind power. This will be a less expensive way to power trains than oil will be in the future.
Trains in the future will be much quicker than they are today. The engines and overall build of the train will more than likely be improved to make travel much faster. The rails under the train will change too. In the future I see them all being replaced with magnetic railways.
Overall our world is constantly changing. New things continue to be made and old things improved. Trains will continue to be used for quite some time. But there are too many possibilities to know for certain whether trains will be improved or replace by a new form of transportation sometime in the future.