The barriers to GIMP adoption are far deeper than the name, as proven by the popularity of Seashore and GimPhoto.
Were I involved with the project, I'd consider a rebrand at the next major release for the sole reason of it being a shit name, and only if the new name was good enough to justify the change and was ready to be accompanied by significant already realised improvements.
I would not fork the code, give it an even shitter name, and waste time replacing all references to a project that isn't going away.
EDITED: 8 May 2020 18:22 by BOUGHTONP