No, never. As far as I can tell, there has never even been a starting outfield of three players who would go on to hit 500 home runs. In 1966, three eventual 500 home run hitters started (Willie Mays, Hank Aaron, and Willie McCovey), but McCovey played first.
There are currently 20 players in MLB history with 500+ HRs. Only three others, besides Bonds, Sosa and Griffey, were ever contemporaries who were outfielders that played in the same league:
Willie Mays(660), Hank Aaron(755) and Frank Robinson(586), NL 1956-1965
They were on the same all-star team in 1956, '57, '59, '61, '62 and '65.
All three started the 1957 All-Star game for the National League, Robinson in left,
Mays in center, and Aaron in right.
The issue is that there are only 20 players to hit 500 homers in their career (with Fred McGriff possibly number 21 this year, currently at 493). It’s a small club, and when you join, you tend to be towards the end of your career.
The season when the most members of the 500-HR club were playing was 1971, when there were five (Mays, Aaron, banks, Killebrew, Robinson). Banks retired after that season, so there were 4 in 1972 & 1973, and the number dwindled to zero by 1977. From 1977 to 2000, there were no more than 2 active players with 500+ homers active at any one time. However, the addition of three new members in the past 18 monyhs brings the current number to 4, with McGriff likely to make it five by season’s end.
For what it’s worth, here’s a chronological list of the players who hit 500 homers. The dates in paranthesees indicates the year they hit number 500 to the year they retired.
But the whole point here isn’t “guys who would go on to hit 500 homers”, its “guys who already have.” That’s what is notewrthy.
if you want to talk about an assemblage of players who went on to do something years later, just look at the 2000 All Star Game. Four guys who hit 500 played that year (Bonds, McGwire, Sosa, Griffey) as did McGriff, who will probably join the 500 club later this year. The game featured four other guys who have a reasonable shot at getting 500 eventually: Gary Sheffield (392), Mike Piazza (374), Manny Ramirez (367), Alex Rodriguez (364).
As for the days with 7 eventual 500-club members in the All star game, that happened four times: 1956, 1957, 1961, 1969. The numbers are skewed to the past of course, not because it was the golden age but because we don’t know which active players might join the 500 club, and those who are close have been around for 15 years.