Basically, if you own it you get a chance in 35 years to make changes. You must provide notice, date, 2-10 years before the date, and record the notice with the copyright office. Any derivative works during the time of the license continue to be licensed even after revocation.
Companies that have a GPL and want to change it typically just increase the version number and change the license at that time. There, the new license applies to that version on, and the older versions stay with the GPL.
17 U.S.C. S203:
In the case of a grant executed by one author, termination of the grant may be effected by that author or, if the author is dead, by the person or persons who, under clause (2) of this subsection, own and are entitled to exercise a total of more than one-half of that author’s termination interest. [There are many conditions on if one person or another has rights.] . . .
Termination of the grant may be effected at any time during a period of five years beginning at the end of thirty-five years from the date of execution of the grant; or, if the grant covers the right of publication of the work, the period begins at the end of thirty-five years from the date of publication of the work under the grant or at the end of forty years from the date of execution of the grant, whichever term ends earlier.
The termination shall be effected by serving an advance notice in writing, signed by the number and proportion of owners of termination interests required under clauses (1) and (2) of this subsection, or by their duly authorized agents, upon the grantee or the grantee’s successor in title.
(A) The notice shall state the effective date of the termination, which shall fall within the five-year period specified by clause (3) of this subsection, and the notice shall be served not less than two or more than ten years before that date. A copy of the notice shall be recorded in the Copyright Office before the effective date of termination, as a condition to its taking effect.
(B) The notice shall comply, in form, content, and manner of service, with requirements that the Register of Copyrights shall prescribe by regulation.
(5) Termination of the grant may be effected notwithstanding any agreement to the contrary, including an agreement to make a will or to make any future grant.