Can StackExchange restrict access to its content?

Question

We are having a lot of fun at StackExchange sites and creating a huge base of knowledge. However, one sad day we may wake up and see that:

1. SE can be only accessed by predefined set of people (for example: "only for SE employees", "only for the US army", "only for users with at least 1000 reputation", "only for active and successful users")
2. SE demands payment for accessing Q&A base
3. I can only read those parts of the SE Q&A base which I helped to create (posted, edited, voted, etc).
4. SE allows its knowledge only to be used for certain goals (ex: "you may not consult StackOverflow create a computer program which will be sold to someone", "you cannot learn for your university exam from SE", "you cannot use RPG SE to help you with your job as a professional game master", "you cannot print and sell a book with SE posts", "you cannot ask Law SE for how long you should put that guy into prison") [yes, I know it's hard to prove]
5. SE "buys" the knowledgebase for bazillion of dollars from the people all around the world and then does some of 1), 2), 3), 4).

Of course, StackExchange (the company) can be shut down and their servers turned off/fail. This is not the problem which I am asking about.

So, can StackExchange restrict access to its content (for example by doing one of the above options)?

Note: I am afraid that asking about each of those 5 points would qualify my question for closing as "too broad", therefore please focus on the question in title.

Answer 1

StackExchange probably has no obligation to continue to provide the content, however StackExchange probably cannot stop copies from continuing to be used, reproduced, etc.

from the Terms of Service (click on Legal below): You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license.

Bold added by me. The content is licensed to SE, unlike some sites where you transfer ownership of content to the site. SE can continue to use your data, but you still own the copyright. They can't limit your use of your own content, because you remain the owner.

SE cannot use your content in a way that violates the Creative Commons Share Alike License, but I don't see any limitations on how SE makes your work available, including to a limited audience. They could, for example, probably move to a paid model because there are no commercial exclusions (unlike the Creative Commons non-commercial variations of the license).

You could post a copy of SE content elsewhere, as long as you adhere to the requirements:

In the event that You post or otherwise use Subscriber Content outside of the Network or Services, with the exception of content entirely created by You, You agree that You will follow the attribution rules of the Creative Commons Attribution Share Alike license as follows:

You will ensure that any such use of Subscriber Content visually displays or otherwise indicates the source of the Subscriber Content as coming from the Stack Exchange Network. This requirement is satisfied with a discreet text blurb, or some other unobtrusive but clear visual indication.

You will ensure that any such Internet use of Subscriber Content includes a hyperlink directly to the original question on the source site on the Network (e.g., https://stackoverflow.com/questions/12345)

You will ensure that any such use of Subscriber Content visually display or otherwise clearly indicate the author names for every question and answer so used.

You will ensure that any such Internet use of Subscriber Content Hyperlink each author name directly back to his or her user profile page on the source site on the Network (e.g., https://stackoverflow.com/users/12345/username), directly to the Stack Exchange domain, in standard HTML (i.e. not through a Tinyurl or other such indirect hyperlink, form of obfuscation or redirection), without any “nofollow” command or any other such means of avoiding detection by search engines, and visible even with JavaScript disabled.

Making a complete copy of SE would seem to be within the terms of the license, as long as all the requirements for attributing, linking, etc are met, so you could mitigate the risk of the SE material going away in that manner.

Answer 2

Numbers 1, 2, 3 are certainly possible.

However, Stack Exchange regularly posts a data dump of all user-created content. This dump is licensed under a Creative Commons license, which is not revocable.

So if Stack Exchange tried to do any of what you describe, anyone who had already downloaded the dump could start a new site with all the current SE content, and invite people to add to it. There would not be anything that Stack Exchange could legally do to stop that, nor could they restrict how people used the content they got from there (other than the existing restrictions of the Creative Commons license, e.g. must include attribution, derivative works must get the same license, etc). As such, 1,2,3, while legal, would be kind of a worthless business model.

In fact, this is already happening: there are third-party sites that repost SE content, with a similar interface and their own ads. Assuming they got the data from the CC dump and they obey the license terms, this is 100% legal.

As to number 4, all user content has been licensed to Stack Exchange under the terms of that same license, which includes "You may not apply legal terms or technological measures that legally restrict others from doing anything the license permits." Number 4 on your list would appear to violate that, and so if Stack Exchange tried number 4, everybody who had ever posted to Stack Exchange would be able to sue them.

As for number 5, Stack Exchange could in principle try to make a deal with every single user to buy the copyright of the user's content. That would give SE additional rights as to how they could use the content (e.g. they could use it in ways that the CC license doesn't allow, such as publishing it without attribution). But that would still not allow them to restrict how other people could use the dumped content. The original author already licensed it to the public under the Creative Commons license and neither they nor any successor copyright holder can revoke it.

Stack Exchange certainly could change the terms of service so that content posted after the change is licensed to them under some other terms than CC. In principle those terms could include restrictions on how the content can be used, though I do not know how far those restrictions could go and still be enforceable.

Answer 3

This issue is coveres in the TOS section 1, which says

Stack Exchange may change, suspend or discontinue the Services at any time, including the availability of any feature, database, or Content. Stack Exchange may also impose limits on certain features and services or restrict Subscriber’s access to parts or all of the Services without notice or liability. Stack Exchange reserves the right, at its discretion, to modify these Terms of Service at any time by posting revised Terms of Service on the Network and by providing notice via e-mail, where possible, or on the Network.

Everything that you suggested is a possibility.