The reason why this statement in the Quran was very daring is because it was revealed ten years before Abu Lahab's death. The fact that Abu Lahab had ten years to believe in the Quran as the word of God is a lot of time. Many of the bitterest enemies of Islam such as Umar bin Al Khattab and Khaled bin Waleed accepted Islam and so many others. Why they and not Abu Lahab?
If Abu Lahab came out 'even if acting' repenting from fear of Allah's punishment and he is finally convinced of Muhammad's Prophethood (peace be upon him) then so many people would have started having doubts in the Prophet Muhammad (peace be upon him).
So this was a daring statement for the Prophet to make taking into the considerations the risks that came along with it. However, since it was a revelation from God we would expect to see that things went according to plan.