Caves, Cliffs, and more

With the new caves coming out wouldn't it be great to have a new mine cart system? Like changeable track with a flick of a lever, minecart with a brake or even minecarts with ores or fossils or something. I think this would make mineshafts a little more exciting and make rail roads more convenient to have. Even a bumper on a cart to make a mob move instead of catching it into the cart or push it off the track. I just thought this would be helpful for people who use minecarts on a regular still.