Nothing, but at least they won't have the largest web properties and the most sprawling ad surveillance network to combine with that browser in ways that are evil and anti-competetive. Silver Lake won't knowingly ship a bug in Google Search or Gmail that breaks Firefox or Safari for a month, peeling off millions more of those users to Chrome which magically works despite the other-browser breaking bug, then rinse and repeat once every 3-6 months for a decade until the competition has no users any more.