The best way to answer that is to say

The ending of future is the end of the "Steven universe" storyline. They might make more in the future but For now they feel satisfied with the ending

He will go back to his friends eventually but for now he wants to find his own purpose in life and find himself

Its saying he will leave them forever, but for now he needs to focus on himself.

1. No, Steven won't be leaving his family and friends behind forever. It's unclear whether he'll move back to Beach City or go live somewhere else, but the finale makes it clear that they will still visit each other at the very least. The additional drawing Rebecca Sugar did post-series shows Steven with the Crystal Gems, Connie, and Greg enjoying some family time. :)

2. There aren't currently any plans to continue the series, but the writers have mentioned being open to the possibility at some point.