This marks the end of an era in a lot of ways. Joel Spolsky's influence on software development can't be understated. Stack Overflow is a huge company with lots of decision makers, so things will carry along without him.
In the post, he acknowledges that Stack will have to keep evolving
The type of people Stack Overflow serves has changed, and now, as a part of the developer ecosystem, we have a responsibility to create an online community that is far more diverse, inclusive, and welcoming of newcomers.
It's pretty interesting to make this announcement without a successor named.
It will not be easy to find a CEO who is the right person to lead that mission. We will, no doubt, hire one of those fancy executive headhunters to help us in the search. But, hey, this is Stack Overflow. If there’s one thing I have learned by now, it’s that there’s always someone in the community who can answer the questions I can’t.