Sacks predicted that following the July 2023 LK‑99 preprints, other research groups would attempt to replicate the reported room‑temperature, ambient‑pressure superconductivity by reproducing the material and measurements.

This clearly occurred:

• A widely cited August 2023 paper "Synthesis and characterisation of LK-99" explicitly notes that the original LK‑99 preprints "str[uck] worldwide experimental research efforts in replicating the results" and then describes an independent synthesis and characterization that found no superconductivity. (arxiv.org)
• Another group published "On the synthesis methodologies to prepare Pb₉Cu(PO₄)₆O" detailing their "various attempts to prepare" LK‑99 using multiple synthesis routes, again as a replication effort. (arxiv.org)
• A separate preprint "Absence of superconductivity in LK-99 at ambient conditions" reports continued efforts "to synthesize phase pure LK-99" following the procedure of Lee et al., explicitly as a replication and test of the superconductivity claim. (arxiv.org)
• Summary articles and timelines note that, after the July 2023 preprints, many different researchers around the world attempted to reproduce the synthesis and measurements of LK‑99 within weeks, with more than 15 notable labs publishing (mostly negative) replication results. (en.wikipedia.org)

Sacks did not predict that the replication attempts would succeed, only that “it will be replicated. People will try and do what they are now claiming they did.” That prediction—about the strong, rapid global effort to reproduce LK‑99—is unambiguously borne out by the record.