No, I would still not agree with it as it seems to be based on the idea that we will not see the benefits before 50 years has elapsed.

As I've already said, I read: "The overwhelming opportunity for Brexit is over the next 50 years." to mean that we will see benefits over (not 'after') the next 50 years.

After all, it's taken us over 40 years to fully realise what the 'Common Market' was going to lead to. We were lied to back then by supporters of joining, and we've already seen that we were lied to (in Project Fear) about the immediate hazards of leaving.