No. CB 3.x will be a gradual release. Technically speaking CB 2.x and CB 3.x will exist at the same time on an install. CB 2.x endpoints and API usages will then gradually move into CB 3.x as they're rewritten. Development on CB 3.x should start end of this year or beginning of next year, but it's first release will probably have very little in it as again it'll be a gradual process.