If he played atleast 85% of his games he would likely have won every art ross from 89-2003 with a few exceptions.
Not so fast...
I think Lemieux would have had three more Art Rosses and he "did lost" those on seasons where he didn't play at all.
1994-95
1997-98
1999-00
1989-90 is debatable, and if we want to give extra games and points for Mario on that season, we should also keep on mind that also Gretzky had an injury. So it's still Gretzky's Art Ross.
On 1993-94 season Mario scored 1.68 points per game. With 85% games played it would have mean 71 games, 55 goals and 64 assists = 119 points. Gretzky scored 130 points for Art Ross.
1994-95 would have been quite sure for Mario. As 29-year-old he was definitely still on his prime and unbeatable. 85% of played games (41 games) estimation with 93-94 & 95-96 average production (2.15 P/game) would have resulted 39 goals and 48 assists = 87 points. Jagr and Lindros got 70 points on that season to split the Art Ross.
1997-98 wit 85% of games and 1.7 estimated point production would have netted 50 goals and 69 assists to have 119 point to beat Jagr for the Art Ross. But at next season, Jagr would have benefitted about Mario's existence to win the Art Ross by himself.
1999-00 would have been Mario's Art Ross again, if he plays 85% of games (70) and will end to +110 points again. Jagr lost 19 games for an injury, but won the Art Ross with only 96 points.
2000-01 Jagr would have been the winner, because Jaromir would have benefited Mario's existence again.
From 2001 until Mario's career end, 85% of games and his point/game rate on those latest seasons would not have been enough to win Art Rosses. he would have been on the race, but not win it.
Estimated Art Ross history, when Mario plays 85% games per season:
1988-89 - Lemieux, 199p
1989-90 - Gretzky, 142p (Lemieux 85% of games estimation 141,7p)
1990-91 - Gretzky, 163p
1991-92 - Lemieux, 130p
1992-93 - Lemieux, 160p
1993-94 - Gretzky, 130p (Lemieux 85% of games estimation 119p)
1994-95 - Lemieux, 87p (41 game estimation, Jagr and Lindros had 70 points to win Art Ross)
1995-96 - Lemieux, 161p
1996-97 - Lemieux, 122p
1997-98 - Lemieux, 119p (70 game estimation, Jagr had 102 points to win Art Ross)
1998-99 - Jagr, 127p (Mario 117p in 85% of games)
1999-00 - Lemieux, 114p (70 game estimation, Jagr had 96 points to win Art Ross)
2000-01 - Jagr, 121p (Lemieux 85% game estimation would have mean 124 points in 70 games, but Jagr would have scored +130 points if he had played almost full season with Mario.)
2001-02 - Iginla, 96p (Mario 90p in 85% of games)
2002-03 - Forsberg, 106p (Mario 95p in 85% of games)
2003-04 - St. Louis, 94p (Mario 63p in 85% of games)
2005-06 - Thornton, 125p (Mario 59p in 85% of games)
With this 85% of games per season estimate, Lemieux lost 548 games, 330 goals and 521 assists on his career. Being able to play 85% of games on every season would have pushed him over 1000 goals (690 + 330 = 1020 total goals) and over 2500 points (1723 + 851 = 2574p).