The Mac will use the ARM architecture with its own Apple Silicon processor, so it will "break up" with Intel. However, the latest Apple support document reveals that Apple Silicon will abandon non-Apple GPUs.
At the WWDC 2020 Developer Conference, Apple focused on transitioning Metal Apps to the new architecture, which also refers to the new Mac will use customized Apple GPU.
Apple GPU software director Gokhan Avkarogullari said that Apple Silicon Mac will use Apple-designed GPU instead of Intel, AMD or NVIDIA.
It is unknown whether the eGPU will appear in the Mac ARM version. It may depend on the compatibility of Thunderbolt 3 and the driver. Although Apple has not disclosed the performance of its own GPU, Apple said it should not underestimate the performance of Apple's own GPU. The new Apple Silicon processor and its built-in GPU are optimized for high-performance graphics.