Comment by VorpalWay

Some countries have national archives that all published material must by law be submitted to, including material published online. I know at least Sweden and the UK has that. This will be available for researchers, though usually you have to physically travel to the archive to access the data, so not as convenient as IA.

(It is worth noting that at least in Sweden "published" here has a very specific meaning, that doesn't include personal websites etc, but it does include news outlets.)