"unity of the faith" is not speaking about what each person personally believes for there will NEVER will be unity in that. 1 Cor 13 does not teach there will be a unity in what all people personally believe but there will be dis-unity until the end of the world.
As the article I posted points out, "the faith" refers to the body of teachings of the NT, as Paul preached "the faith", Gal 1:23.
Paul did not preach one faith to one group and a contradicting faith to another group, but taught the ONE FAITH to that ONE BODY, Eph 4:4,5. a question asked so often "What faith are you" is very unbilical for it is assuming there are many faithS each person can choose among.
That body of teachings was perfected/completed by the end of the first century with John writing Revelation and the gifts ceased, vanished away.
So the gifts would last "till" there is a unity/oneness of the body of NT teachings, which occured 2000+ years ago. Gifts were given to various functions (verse 11) but while the gifts ceased some of the functions continued. The office of an apostle was meant to be temporary in revealing and confirmation of that body of NT teachings along with initially taking the gospel to the world. Prophets ceased when gifts ceased. There are still evangelists, pastors and teachers but none have the gifts.