Storage (NAND flash) and many off-chip communication protocols (both wired and wireless) are already non-binary and use multiple discrete voltage levels. There'

Storage (NAND flash) and many off-chip communication protocols (both wired and wireless) are already non-binary and use multiple discrete voltage levels. There's also a lot of interest in more or less analog storage and compute elements for ML, where it's fine to have weights and activations represented in a fundamentally fuzzy manner. But I don't think there's any promising way to perform discrete deterministic logic and computation in base 3 or higher using transistors, aside from what we already do for multi-bit quantities.