Comment 1 for bug 1391963

CUPS 1.6 will have major incompatible changes:

"Transition all non-Mac filters to OpenPrinting"
http://www.cups.org/str.php?L3930
"Deprecate and stub out image file support"
http://www.cups.org/str.php?L3931

"Drop serial and parallel backends"
http://www.cups.org/str.php?L3935

"Drop support for CUPS Browsing and Polling"
http://www.cups.org/str.php?L3922
"CUPS browsing is deprecated and scheduled for removal ... after 1.5.x"
http://www.cups.org/str.php?L3889
"Bonjour is the replacement"
http://www.cups.org/newsgroups.php?gcups.general+T+Q%22Why+is+CUPS+browsing+deprecated%22

"Deprecate PPD functions"
http://www.cups.org/str.php?L3926
"Deprecate the PPD compiler"
http://www.cups.org/str.php?L3927
"Support for PPDs is not going away in CUPS 1.6"
http://www.cups.org/newsgroups.php?gcups.general+T+Q%22CUPS+1.6+and+PPD%22

In general for changes in the upcomming CUPS version 1.6 see
http://www.cups.org/roadmap.php?VERSION=1.6