I would suggest that the real path will be a synthesis of live action and CGI. MoCap sequences performed by celebs to capture the nuances of their skill and performances, but the directors would then be able to modify and play what if in post to further enhance and manipulate the original performances. To master all of the individual crafts required to generate a masterful film would take multiple lifetimes to learn. Remember, even if a young Spielberg had all the techno toys he could imagine, Im certain hed be the first to admit that hes still not the skilled performer.