If significant numbers of people were to observe the Seven Laws there would be a visible decline in cruelty & injustice of all kinds, both on the personal & on the social level. They would not only enable mankind to have one law but the law would be of an everlasting nature.
The acknowledgement of His sovereignity itself provides the unifying factor, without the need for any other philosophy, system of government or new discovery."The L-rd is good to all, and his mercies are upon all his works"(Psalms 145:9)
If mankind were to strive to uplit itself to realize an idealistic universal Utopia can indeed exist, perhaps one might see how accepting the system of the 7 Noahide Laws serves as an answer to achieve that goal, thereby creating a finer world in which peace, happiness, freedom & equality emerge supreme!