Either one of two things: a) like normal employees now, VCs insist founders vest over 4 years, so what he has vested he keeps, or b) the board says he was fired

Either one of two things: a) like normal employees now, VCs insist founders vest over 4 years, so what he has vested he keeps, or b) the board says he was fired 'for cause' and can claw back ALL his equity (many but not all contracts have such provisions)