Conversation so far:
Was Frank Gifford's broadcasting career a success?
In 1971 Gifford replaced Keith Jackson as Monday Night Football's play-by-play announcer, and remained involved with the show for 27 of its next 28 years.
Where did Frank Gifford work as a play-by-play announcer?
In 1971, Frank Gifford replaced Keith Jackson as Monday Night Football's play-by-play announcer for CBS.
What sports did Frank Gifford broadcast?
Frank Gifford became a broadcaster for CBS, covering football, golf and basketball.
How long did Frank Gifford's broadcasting career last?
Frank Gifford replaced Keith Jackson as Monday Night Football's play-by-play announcer, and remained involved with the show for 27 of its next 28 years.

Question: Why did his broadcasting career end?
Self-contained rewrite: Why did Frank Gifford's broadcasting career end?