High accuracy long read DNA sequencing. The new chemistry for Oxford Nanopore is getting close to where you can use it exclusively without polishing (down to ~1 in 100 base errors), and the price per gigabase has become competitive with Illumina (but with reads in the 10s or 100s of kilobases in lengths). On the other hand, PacBio HiFi reads are really reliably high accuracy and still long enough to resolve complex variants missed by Illumina, and only ~2x more expensive than ONT.

Both technologies totally redefine what we mean by "sequencing a genome" and open up broad categories of mutations that are completely invisible to more common forms of genotyping or sequencing.