We got Kim at The Grove in Los Angeles Wednesday and our photog asked about her latest accomplishment, making it onto Forbes' official list of billionaires.

Kim says she's feeling blessed to have finally reached the milestone, thanks in large part to her KKW Beauty and SKIMS brands, and she sounds pretty confident she and Kylie Jenner won't be the only billionaires in the fam when the dust settles.

Kim was at the outdoor mall, btw, promoting SKIMS ... so, she's not taking her foot off the gas just because she's got a billie in the bank.

We asked who she thinks will be next up in the club for the Kardashian-Jenners, and she gave it some good hard thought. We suggested her mom, Kris, or maybe Kendall Jenner -- but Kim's thinking bigger, and says the bucks won't stop with those two!!!

No pressure or anything for Khloe, Kourtney and Rob. Not to mention North, Saint, Chicago, Psalm and -- well, we're not gonna run down ALL her nieces and nephews too. You get the point.