Last year, I wrote to let you know that the powerpc architecture would be
dropped from zesty as of Feature Freeze.
We are well into Feature Freeze at this point, so an update is overdue. As
of Feature Freeze in February, the status is that powerpc packages are no
longer considered for proposed-migration, and we have discontinued all CD
image builds for powerpc in zesty.
For the moment, uploads continue to be built for powerpc in Launchpad, and
packages are still published in the archive. You should expect both to be
discontinued before the 17.04 release.