While it may seem odd at first that after the heavy influence of Freeza's empire, they disappeared after Freezaa and his father died (save for the 2008 Special, DB Online, and the Cooler movies), I think it makes perfect sense.
In our world's history, civil wars have erupted in empires after the death of the leader. That just weakens the empire even more and ultimately, they collapse. I believe that is what happened here. Freeza and King Cold could control their empire of numerous planets (100+?) because of the overwhelming power difference between them and their subordinates.
On Namek, Kui, Dodoria, Zarbon, and the Ginyu Squad died (save for Ginyu who was trapped in a frog's body) and Vegeta defected and eventually settled on Earth. With Freeza and King Cold dying as well, that would leave parity amongst the remnants. With all the top guys gone, I imagine that there was a massive civil war as different factions vying for power erupted. Many more would die and while some factions might get some power, it would be nothing compared to the totality of Freeza's empire at its peak. In time, those factions would probably have civil wars themselves as subordinates may feel they can take out the top guy by banding together.
TL;DR: I believe that Freeza's empire collapsed on themselves due to civil wars.
Collapse of Freeza's Empire Theory
Re: Collapse of Freeza's Empire Theory
King Cold was part of a secret board of executives that governed the galaxy behind closed-doors.
I would guess someone else just bought his seat or replaced him.
There's other powers at play here, space is a vast place.
I would guess someone else just bought his seat or replaced him.
There's other powers at play here, space is a vast place.
That time your teacher asked you to draw Cell in biology class.
This man is my hero:
This man is my hero:
To be perfectly honest, I couldn't care less about the fans a re-issue might alienate because if all they're concerned about is being able to scalp the people who were either unaware of the Dragon Boxes or couldn't afford them at the time, they're just leeches and deserve to have their greed backfire on them.