Abdul-Jabbar - 5660 Ast. in 1560 games (37MPG)
Chamberlain - 4643 Ast. in 1045 games (46MPG)
Jokić - 4101 Ast. in 612 games (31MPG)
Russell - 4100 Ast. in 963 games (42MPG)
https://www.statmuse.com/nba/ask/most-assists-in-a-career-by-a-center
Isaiah Thomas is at 9061, so Jokić would need 4960 more. In the last 5 seasons he had an average of 8 APG, or 656 assists per season. If he keeps that up, he’ll be there in 7-8 seasons.