(Adds background, Kudrin detail)By Alexander MarrowMOSCOW, Dec 30 (Reuters) - The co-founder of Russian internet giant Yandex, Arkady Volozh, said goodbye in an internal message to staff on Friday ahead of a corporate restructuring that could see ownership of many of the firm's core services change hands.It sold its news feed and homepage to state-controlled rival VK this year, in part to try and depoliticise its business, a source close to Yandex said."As you know, I haven’t really been involved in Yandex’s Russian business for some time, but this year I had to step down from the company completely," Volozh said in the message, seen by Reuters.Yandex's Dutch-registered holding company last month said it planned to divest ownership and control of most of Yandex Group, including its main revenue-generating businesses, a move that could lead to enhanced Kremlin influence over some of Russia's backbone internet services.The international divisions of Yandex's self-driving technologies cloud computing, data labelling, and edtech would then be developed independently from Russia."