I am testing Magento 2.2 RC with snowdogapps/magento2-theme-blank-sass. However, when running composer require snowdog/theme-blank-sass I see this problem:
snowdog/theme-blank-sass 0.10.1 requires magento/framework 100.1.* -> no matching package found.
As of today, Magento 2.2 RC comes with magento/framework 100.2.0-dev
It seems the theme currently doesn't support Magento 2.2.
You can see the available versions on the readme file https://github.com/SnowdogApps/magento2-theme-blank-sass
Maybe you can create an issue https://github.com/SnowdogApps/magento2-theme-blank-sass/issues to report this situation.