Longevity risk: The uncertainty of how long he will live after retirement affects the adequacy of savings. If he lives longer than expected, his savings may not be sufficient. Inflation risk: While inflation is assumed to be 0 after the retirement period, there may be unforeseen changes in the future. If inflation rises, it can erode the purchasing power of his retirement income. Healthcare costs: The cost of healthcare can be a significant expense during retirement. He should consider potential healthcare expenses and factor them into his savings plan. Market volatility: The rate of return assumption of 4.5% may not hold in the future due to market fluctuations. He should be prepared for potential variations in investment returns and adjust his savings plan accordingly.