Unsafe Pass will stay, and it is a concept inside the new RenderGraph API. But you need to take care of managing the resources yourself and you opt out of automatic optimization.
If you use the recommended Raster/Compute passes, you will be able get future optimizations e.g. from us or from the hardware vendor implementations, while this is not guaranteed in an unsafe pass, since we don’t know what is happening inside. The whole idea of RenderGraph is to lay out the rendering strategy (dependency graph) for the whole frame, to optimal use the resources, merging sub-passes and ideally stay on tile on mobile GPUs, which reducing the texture bandwidth and therefor optimizes battery consumption and performance (e.g. no throttling).
At GDC we did an in-depth presentation on this. I hope the recording will get online soon on Youtube so that I can post the link here.