If you use a value to do a calculation and it's from the future then often you end up blocking until it's available. This is how a Future works and is similar to what happens when you read from a TCP connection and the data has to be retransmitted because the network dropped the packet, so you block. If you want responsive output then you should avoid blocking or at least have a timeout and/or cancel button.

The conceptual idea of a value that continuously changes is nice for animation or maybe video (though that's both discrete and lossy), but seems messier when your knowledge is limited to an unknown selection of discrete data points from that timeline, arriving with an unknown amount of lag? Maybe you could talk about that mathematically, but it seems like it's going to be rather abstract and messy.