I agree that comment was poorly worded and confusing. I think what they might have meant was AMZN would have to earn $500B of profit over the next several years

I agree that comment was poorly worded and confusing. I think what they might have meant was AMZN would have to earn $500B of profit over the next several years and based on 3% profit margin that would need $16T in revenue to earn that amount of profit. The math works out to approximately 7 years, though the comment just wrote "some time in the future".