It's usually not worth claiming it, but it seems like there is an argument for constructive dismissal here.
Isn't constructive dismissal just a way to get unemployment, and you would get unemployment anyways with a layoff or involuntary termination?
However, if they were "constructively dismissed" that is treated as a layoff/involuntary termination and the employee can get unemployment.
Note that the OP mentioned that their remote work agreement was voided. They weren't constructively dismissed, it sounds like they were actually terminated. (A company can't simply decide to unilaterally void part of an employment agreement without voiding the entire agreement. That's not how contracts work. )
Either they will either quit voluntarily (stupid) or they will be terminated.
They haven't been terminated because they are still working until August at least. It sounds like they were given until Friday to sign a revised employment contract without remote work or the company will take action.
Constructive dismissal usually comes up for hourly workers that stop being scheduled but aren't fired. For a salary employee it is usually cut and dry, either the employer is sending you a check or they aren't.