How do flyback diodes (on an H-bridge) affect the motion of the motor?

I'm designing an H-bridge and one of the features I'd like to have is to allow the motor to keep it's momentum even when the H-bridge is off.

Obviously flyback diodes are used in H-bridge designs to allow the coils to discharge. I feel like I don't have a very intuitive understanding of this concept, but my hypothesis is that this will cause the motor to stop spinning (or at least slow down a bit until the voltage on one of the motor's terminals is no greater than the power supply +0.7V). Is this correct? What does this mean from a mechanical perspective?