I believe that answer is only partially true.
I THINK that if nobody signs an IFA after a certain period of time, he just shows up in the IFA list for anyone to sign.
I still maintain that I was never notified about
Luis Vasquez as an IFA in Season 9. At the end of the season, I went out to the IFA list to see who was available to spend the rest of my unused budget on, and he was there. I threw every penny I had at him, and <BAM> he signed the next cycle.