I'm convinced that the room temp superconductor is real for a couple reasons- the academic infighting around who gets credit and the nature of the evidence (more can be read here: https://en.wikipedia.org/wiki/LK-99). Superconductors allow magnets to float on them via the Meissner effect- if we scale this up in time, we can have a floating city before 2050. I'll define "floating city" as a settlement that levitates 10 feet off the ground and houses 450 people.