First, he'd have to play two more years to reach the required minimum of 10 MLB seasons to be eligible...
In that regard, maybe Kirby Puckett is a better comp than Rice; Puckett only played 12 years and finished with 51.2 bWAR, so Betts would have to average 1 WAR for the next four years to pass him. Kirby and Mookie each have three Top 3 MVP years, two World Series rings, one batting title, multiple Gold Gloves. Puckett led the league in hits four times, Betts led the bigs in runs scored twice. Kirby has an RBI crown, Mookie led in slugging, and tied a record with six career three-HR games (at age 27).