18-year-old on an h4 visa

Can an 18-year-old on an h4 visa stay in the US if his father who has an h1b visa leaves the US?

H-4 visas are issued to the H-1 holder's spouse and children under twenty-one years of age. Holders of H-4 visas are considered to be dependents of H-1B visa holders. As H-4 status holders, spouses and children under twenty-one years of age may be entitled to enter and remain in the United States for the duration of the H-1 holder's authorized stay.

Therefore, an 18-year-old on an H4 visa can NOT stay in the US if his father who has an H1B visa leaves the US. But H-4 a visa holder may later adjust his status to anyone of the following: H-1, F-1, B-1, B-2, and other non-immigrant status.