There could be... but with Epona, I don't really think you will need trains :p

Maybe something that you can fly with like in Skyward Sword

Sheldon Cooper likes this ;P

Actually, I thought about this as well. It's just a crazy idea that I have, but let a man dream.
I think this game is going to be huge and epic, and just to celebrate the series 30th anniversary, it will have things from all of the previous Zelda games such as the train from Spirit tracks and that lovely overworld music, Midna from twilight princess, light/dark world from a link to the past, child/adult link from ocarina of time, the feather from link's awakening, painting mechanic from link between worlds, our favourite characters from all of the previous games, the loftwing from skyward sword and so on.

I know some of those things would be impossible to put together on the same game, but it's a nice idea I think. They could do like a reboot of the saga, with fans favourite things, places, items, characters, enemies and bosses, and many new things.

i wont think it would fit into the world

I dont believe we've seen anywhere else besides the forest. I remember the gameplay video at the Video Game Awards show we saw some buildings.

Nope. That's your only train is called Epona and it's a horse.

I guess there could be trains but I can't say the idea excites me in the slightest. The world in Zelda U is supposed to the big and traversing a big game world using a train sounds kinda boring. Traveling in Spirit Tracks made me crazy and that world wasn't very large.

Oh, you've thrown down the guantlet! Time for the boldest prediction, ever....

It will feature some kind of transport for sure, but I don't think trains would fit in this world.