You can't interpolate into the future, because you are lacking a future data point. The best estimate of your current speed is the last reading. Position is different because the equations of motion do allow a good approximation because velocity = distance/time therefore an interpolated distance can be obtained from distance plus delta distance / delta time. If you know what I mean.
Velocity offers no clues, or trend, except that delta velocity is limited by mass. Even then, it is influenced by unpredictable factors, e.g. a car might be able to stop faster than it can accelerate. Also you can not predict when the brakes will be activated.
Given some velocity and inertia, you can approximate future velocity because it is an integral. But to improve on the accuracy of the last reading, you would need to know the forces of acceleration that are at work.