Not very far tbh. The basic concepts of how to arrange transistors to do useful work are well understood and have been since before the transistor was invented. The biggest problem that major cpu manufacturers face is how to physically create those cpus. The industrial process that brings us those techniques are technological marvels, but the engineer absolutely know what they want to do, just not how to do it. https://www.tomshardware.com/news/intels-long-awaited-fab-42-is-fully-operational