One mitigating tactic for websites linking other people's content is to create a local copy and display that copy if the original content has been removed or de-linked. Though this may not be 100% kosher copyright-wise.
But speaking of preserving old link structures, would you suggest a strategy for doing so?
On my own blog, I have gone through several movements, either from one blogging platform to another, or more recently, deciding that I liked /blog/title/ better than /blog/year/month/title/. In each case, I have been very careful to ensure that I have a sufficient set of mod_rewrite rules configured in Apache that any of my old URLs will redirect the user to the new URL.
In the case of changing structure wholesale, it was as simple as setting up `RewriteRule ^/blog/\d+/\d+/(.+)$ /blog/$1 [L,R=301]`
In previous cases, I had to get a lot more specific; eg. articles with the same title would have different generated URLs depending on the blog software, so I would need to handle that as a redirect as well.
But speaking of preserving old link structures, would you suggest a strategy for doing so?