The automotive industry is undergoing a fundamental transformation in Electrical/Electronic (E/E) architecture, evolving from traditional distributed and domain-based designs toward zonal configurations. The rapid growth of software-defined functionality, cross-domain integration, and centralized computing has exposed inherent limitations of legacy architectures in scalability, wiring complexity, and system integration. Zonal E/E architecture addresses these challenges by consolidating computing and Input/Output (I/O) resources into high-performance controllers distributed across physical zones of a vehicle. This transformation, however, cannot occur instantaneously, as contemporary vehicle designs and E/E system solutions are the result of decades of incremental development based on distributed and domain-based paradigms. Moreover, key enabling technologies for zonal E/E architecture—such as high-performance Central Compute Platform (CCP) and zonal controllers, high-speed automotive Ethernet, and standardized software architecture—are still maturing. To ensure safety, reliability, and cost-effectiveness, Original Equipment Manufacturers (OEMs) must therefore adopt carefully planned evolution strategy to progressively consolidate functions, realizing the zonal design step by step. This paper proposes a unified architectural framework that systematically maps the full spectrum of evolutionary paths toward zonal E/E architecture. The framework identifies major transition stages, key engineering activities, and alternative migration paths, including distributed and domain-based architectures, vertical and horizontal function integration, various domain fusion patterns, mixed E/E architecture, continuous function migration to CCP and zonal controllers, and ultimately, the full realization of zonal E/E architecture. By organizing and contrasting these evolutionary paths, the framework provides OEMs with architectural insight and practical guidance for planning low-risk, staged transition toward fully zonal E/E architecture capable of supporting next-generation Software-Defined Vehicles (SDVs).