The premise is entirely unrealistic since the difference in orbit parameters. We aren't talking about some slight misconceptions; reality completely walks out of the window in Gravity:

* Most satellites and all crewed spaceships orbit Earth from west to east. Why would they hit each other?

* There is no way to travel between the Hubble and space stations like the way it happened in the movie. Especially not with that EMU with 25 m/s delta-v. That's like taking a cup of kerosene, pouring it into a Boeing 747, and traveling 9000 km. Hubble and the ISS have completely different orbits with different inclination.

* Overall, writers of Gravity have no understanding of orbital mechanics whatsoever.

* ISS orbit height is something like 400 km, for Hubble it's about 550 km. Most communication satellites are orbiting the Earth thousands of kilometers above the sea level. A circular geosynchronous orbit is 35 786 km above Earth's equator.

As for the ISS, the majority of debris created by recent India's incident are 300 km above the sea level. ISS is about 100 km higher.

According to this https://www.spaceacademy.net.au/watch/debris/orblife.htm objects with 300 km altitude will enter atmosphere in a month.