I nurture the idea in my head that further in the future it's peridot that has to shatter the diamonds or goes to war with them after steven defeats them. Maybe he just shows other homeworld gems what life could be like free. Diamonds don't like this and do bad things. Enough gems run away or set up bases on other planets. Then peridot went to war because she lost the love of her life lapis to attackers from homeworld and blames the diamonds. She modifies herself and goes to lead the new rebel gems in space and fights with the diamonds until she wins but is now the new 'logical' leader but with a heart of gold. Jasper gets uncorrupted and redeemed by the way in my au.