Now this is an interesting topic. Samsung may be going with Tizen to avoid both the influence of Google and also to drop license fees it's required to pay to various patent holders that Android OEMS pay to, like Microsoft, and Google licenses. There is also the advantage of Tizen being a lighter OS, making it easier to get it on lesser hardware, and cheaper by avoiding the fees.
Tizen was started before Android One, and the latter may take something off the Tizen advantage. Brings me to this, can Android one give Samsung a beating in the entry level market enough for Samsung to just consider opting for it?