Yes, and presumably the kids would manage the charity.
Or maybe not. Up to him/them. But that's what I'd do.
His public statements have been along the lines of deploying the money in the Gates Foundation before their deaths. Exactly because he doesn't think another big foundation existing forever will do much good.
The Foundation won't be around forever. Its been setup to spend all of its funds within 20 years of Bill and Melinda's deaths.