Frequently, I stumble upon questions that are purely hypothetical and assume a specific technical base which does not yet exist. What I mean are questions going somewhat like this: "…let's assume that everyone has a quantum computer…" or "…is this or that algorithm theoretically secure in case technology advances in this or that way…".
From my point of view, such questions may fit better into philosophy or science fiction, as they are not really about "cryptography" but - at it's best - about "a possible future of cryptography in case technology should evolve a specific way". Simpler said: I have some doubts that such hypothetical questions based on assumptions really belong on cryptography.SE because any answer to such a hypothetical question based on assumptions can only result in hypothetical answers based on more assumptions.
Which takes me to my question: How much science fiction should be handled here "in theory"?
In other words: I have a hard time finding that small line between "they fit in here" and "they don't fit in here". If such questions fit cryptography.SE, what's the reason they do? And if they don't fit in here, how should we handle such questions? Simply by flagging them with an "off-topic - The question is based on assumptions about a theoretical future which is not guaranteed to become reality" or something like that?