This is a rather complex question to answer. At the beginning of the series, Shinichi was evidently desperate to regain his normal form (for example, he fell asleep in class, and frequently asked Dr. Agasa about the men in Black). In fact, during the first two occasions when he regained his normal form, he planned to leave his childhood alter ego behind for good (which, as we all know, didn't happen).
However, over time, Shinichi realized that he was going to be in his child form for a long time, so he gradually adapted to his situation, even going as far as acting like a little kid nearly flawlessly. However, there are still some occasions where he wished he were back to normal (for example, episodes 242 and 246).
Like most other people, I do believe that Shinichi will regain his normal form for good by the time the series concludes, but the producers have purposely delayed letting it happen to avoid taking the air out of the series.
In the unlikely event that Shinichi cannot regain his normal form for good, I think what he would do is simply disclose his true self to everyone after the Black Organization is taken down. I am currently writing a fanfic on how this could hypothetically happen - by the time I upload it, it will be more than 20 pages long, so be patient.