Nobody knows, but for what it's worth, existing large projects that are used in production environments have been fairly good at keeping up with Zig releases. See: Bun, Ghostty, and Tigerbeetle for good examples of this. Because the semantics of Zig are relatively simple, porting to the latest version is usually as simple as bumping your compiler version, trying to build, making a fairly mindless, mechanical change, and repeating until it builds.

The biggest thing holding me back from using Zig for important projects is the willingness of my peers to adopt it, but I'm just building projects that I can build myself until they are convinced :)