Marvel Studios & Disney have today announced that the upcoming Black Widow movie will be delayed until November. November 6, 2020 is now the official release date now schedule for the beginning of the MCU’s Phase 4.
The wording used signifies that all other Marvel movies will be pushed back. Regardless of their original release dates, all MCU films will be pushed back to accomodate Black Widow. Without a complete re-shuffling of their timeline, it could cause chaos for their canon-based plots.