The key to this is the MCU are an independent studio designated with time, funding and focus on just their super-hero output, Marvel Studio's have earnt that, WB are not in a position to have that or seemingly not 'split' to taking DC separate to the natural fold, until that where to happen, if, then it will spread it's focus. WB have had HP to 'fall back on' for years but even that looks like it's losing a lot of support in it's HP / FB existence, I think until DC are made to be a separate venture, no one person will take the reigns.