One way to start to repair their reputation would be to responsibly disclose some vulnerabilities and then take credit for their disclosure. That might motivate whitehats to join them, and whitehats are exactly the type of people they need.
In 10 years, the US is going to be in trouble unless they can continue recruiting good hackers. In 20 years, they'll be in serious trouble when foreign powers have clearly begun dominating the SIGINT arena. And at the rate technology is changing, those timelines seem optimistic.
The NSA can likely get all the recruits it needs by just offering the chance to hack with legal immunity.