Some points before people starts panicking:
The hack took place between March and May 20 of this year
The hackers needed to know the email addresses, passwords and phone numbers linked to the affected Coinbase accounts, and have access to personal emails
Although obviously Coinbase said that there's no evidence that the users' data comes from them, it looks too much like it. Either somebody from inside has sold users' data to a malicious 3rd party, either Coinbase user database was hacked and they didn't notice. Of course, from there to actually accessing users' e-mails there's still some work to do.
The warning, however, is the same as always:
don't keep at centralized exchanges too much money and for too long. Not your keys, not your coins.
I heavily use Coinbase, since their user interface and features are actually great, although I still have worries of having my account hacked, I'm actually glad that my Coinbase account did not get breached. It could either be a breach under Coinbase's DB and since they were able to breach through their 2FA feature, anyway, I think I'll consider switching wallets or at least not let my holdings stay here for a long period of time.