Suppose a package XX has a version-A under GPL-V2 and a forthcoming version-B. Suppose also that version -B is a severe modification of version-A. Now if version-B is to be released under GPL-V3 and suppose the earlier version is also to be maintained for some time, then I believe that the code from version-A would not be usable in version-B. Or how is this migration handled ?
Best
A. Mani