dpkg >= 1.14.6 supports the use of a "Homepage:" field in debian/control. This should replace the Homepage pseudo-field in extended descriptions.
1.A Add Homepage to Debian Policy Manual.
1.B Make lintian stop issuing "I: unknown-field-in-control homepage".
2.A Implement support in APT frontends.
2.B Adapt developer documentation such as the Developer's Reference.
3. Make linda and lintian issue a warning to packages including a homepage in their extended description.
A related bug: 339829
4. After some time, announce mass bug filing on debian-devel-announce.
5. After some time, proceed to mass bug filing.
This page is based on [http://lists.debian.org/debian-devel/2007/09/msg00628.html a message from Christian Perrier to debian-devel] and the resulting thread.