In these cases, the decision-maker has the option, but not the obligation to refuse the application on...
Schengen Visa Refusal: Justification for the purpose and conditions of the intended stay was not provided
...because when the travel dates are passed, the application's premise may no longer be tenable and hence the application is 'incoherent'. This is how Schengen decision-makers are taught to apply the rules.
This draconian outcome may not be the case for your friend, but it is always out there in situations like these. We are not prophets and there is also a likelihood the application will be approved.
You can also search the TSE archives here for 'post-submission anxiety' and advise your friend to brass it out.