If we can recap about missiles like Bora, Lora (Israel), Iskander (Russia) and BP12 derivatives (China) ; These are all quasi ballistic missiles (They behave like ballistic. But have a lower altitude flight paths) . They expend their fuel when they reach their apogee. So they start to lose speed. Then they start their dive from 40-60000m altitude towards earth. Because of rarified atmosphere and almost non existent air drag they reach hypersonic speeds under gravity. But after 15000m altitude when they start hitting denser air they start losing speed governed by terminal velocity principle.You have just explained very well terminal stage when the rocket is free falling at maximum range app 300km.
What if the rocket engaged onto ship at midcourse when its rocket engine still running? İmagine that the Bora engages on a ship at 100km range. İt would still have thrust in order to keep direct flight path. Could Bora keep direct flight path at least 50meters above to sea if it had decent canards and fins?
Kinda big and heavy SAM engaging on ship, Like penguin Anti-ship missile but huge. İ wonder if it would be still hypersonic.
If some fuel were to be kept at reserve like it is in a dual pulse rocket motor, then theoretically you could achieve hypersonic speeds at terminal stage.
These missiles are essentially of ballistic nature. They do not fly like a cruise missile. They go up then down. In fact the more acute the hitting angle the more effective they are and more difficult to intercept. The trick lies in the weight of the missile and it’s aerodynamic structure. The heavier and the more aerodynamic the missile is the less drag coefficient it will have. Hence faster terminal velocity. To make it more difficult to lock on to and intercept, Iskander missile, for example, does certain manoeuvres along it’s flight.