> On the contrary, I see Reddit as being extremely difficult to replace, precisely because of those 17 years of investment by users. Reddit is a gold mine of information related to any topic you can imagine, and that information won't magically migrate to another platform without serious network traction by a large user base.

It doesn't have to. An archive won't save Reddit if the action wants to move elsewhere.

If a particular topical community gets going somewhere else, the most popular information will quickly get recreated just through its normal operation.