A long, long time later, when the grudges between the Decepticons and the Autobots were finally resolved.
When Roadblock and Bumblebee finally get together, fate plays another trick on them.
When Roadblock travels back in time to save Bumblebee, he discovers that no matter what he did, no matter what he changed.
Destiny will always move towards that irreversible future, and there is nothing he can do.