By all means, put the plastic piping for radiant into the floor. It's really cheap to do now. Worst case you don't use it. Best case is you do and it's there. There's nothing better than laying on your back in the winter under the car on a warm slab. A friend of mine has it in his garage floor. He uses a pellet stove to heat it, and while I don't know all the details, it's a closed loop always using the same water to heat the floor, and there's
antifreeze of some sort in the water so that when he doesn't need to use the heat freezing of the water is no issue. Put it in, I sure regret that I didn't.