From an entry on the Stack Exchange blog, "Stack Exchange 2.0", posted 2010-04-13:
Existing Stack Exchange sites will be kept open, under existing rules, for at least three months, and at least one year if you have an active site (defined as ten or more visitors or more on April 8th).
We’ll give you at least 3 months notice before shutting down any site.
How do I know how long my Stack Exchange site will remain open?
Update
Interview with Lead Developer David Fullerton, a new entry on the Stack Exchange blog posted 2010-05-26.
It includes:
For someone who already has a site on SE 1.0, what should they be doing now to prepare their proposals?
The most important thing to do now is focus on your site and your community. Don’t worry about the proposal process right now. You’re building support for your site and that’s the most important thing. The biggest role you can play in the new system is to shore up your site and your current user base. Whether it comes down to migrating your site or creating a new site, you’re establishing what works and does not work in your community.
In the Mixergy interview Joel Spolsky effectively said that at least one year really means indefinitely, but they can not promise more.
Is there a closing date or will this site continue indefinitely?
Just read the post a moment ago and I’m still under the shock. I’m still unsure whether I should export all content to an open source SE clone and keep the site running on my own or simply give up ownership to StackOverflow inc…
Interesting question: how many visitors on April 8th? Of all days, I was flying to NYC that day. Would hate to hear that there were only 9! (Though I probably ‘visited’ early that morning.) =)
I think the 1.0/beta sites should wait a few days to see how the SE authors respond.