During Newsrama interview with Rebecca Sugar and Lamar Abrams, It seem she accidentally confirm about Season 5 being the final season of Steven Universe
"I have big plans for that season!" said Sugar. "Endgame or not I'm shooting for the moon, I'm going to write us into a serious corner!"
Lamar Abrams also say this
"I have no idea…I’ll draw as long as Rebecca wants me to."
It's sound that they are planning big for Season 5 which means that Steven Universe will come to end! :(