By definition... apparently not. Lots of bikes still being made and sold with side-pull brakes. But disc brakes sure are cool.
obˇsoˇlete
adjective: obsolete
1. no longer produced or used; out of date.
"the disposal of old and obsolete machinery"
synonyms: outdated, out of date, outmoded, old-fashioned, démodé, passé, out of fashion; no longer in use, disused, fallen into disuse, behind the times, superannuated, outworn, antiquated, antediluvian, anachronistic, discontinued, old, dated, archaic, ancient, fossilized, extinct, defunct, dead, bygone, out; informal prehistoric
"most of the machinery in their Somerville plant is obsolete"