They will definitely not be able to debug what they built at a certain point. I think their strategy will be to delete parts of the application, and rebuild them, but this will not be sustainable. This comment (and similar ones) helped me to detach from the project's quality and code, and see the business opportunities that may arise in the near future. I think there will be a lot of maintenance, and someone has to make sure the infrastructure and integrations with other systems and platforms won't collapse.