A new API, which gives more autonomy to marketplaces using VTEX, is already in stable. It's the Change Seller API, and it brings a new status to the order workflow, called Window to change Seller.
With this new status, marketplaces can recover sales that would be otherwise lost should a seller canceled an order. Now, they will still have time to find another seller with the requirements to accept the order and ensure conversion.
The "Window to change Seller" status is only available when both Marketplace and Seller are VTEX users. If there's no VTEX seller with the necessary inventory, the order will not proceed to the new status and will be canceled automatically.
This new feature allows marketplaces to have a more efficient quality control on the overall buying experience because they can also choose a different seller when the order status is "Pending payment" or "Awaiting authorization". Another possibility is for those stores that have whitelabel sellers: now they're able to change the seller responsible for an order.
To know more about the Change Seller API, read this VTEX Help article.