I think there are a lot of founders who don't code on their company's product anymore (though it's apparently not a pure factor of size – Gates and Zuckerberg are known for actually writing code many years in), but it'd be weird if they didn't write code at all. It would imply that writing code is never the most efficient way to accomplish a task that they want solved. Even with infinite resources at your beck and call, it's often faster to write a quick script than to explain to someone else what that script should do (and to continue to do so through whatever iterations seem appropriate).
I'm tempted to say that those who don't continue to hack were never really hackers in the first place. For a hacker, writing code is just one of the normal ways to interact with a computer.
I think there's an even more subtle implication that pg is too busy (and should be) to code, yet he still CHOOSES to continue to code. Obviously it would be really easy to find someone to do the coding work - whether keeping up with HN or the creating investor/startup interface - but his choice to continue coding is a statement he and the article are making.
I'm tempted to say that those who don't continue to hack were never really hackers in the first place. For a hacker, writing code is just one of the normal ways to interact with a computer.