Why would anyone buy that idea, with Gazprom involved, especially with them holding a majority stake? How would German part involvement help? They are hardly those most affected.
Putin seems to be pushing this idea quite hard, (www.premier.gov.ru, January 8; Interfax, January 7, 8, 11; German ARD TV, January 11; Nezavisimaya Gazeta, January 13) but what do Europeans gain? It's not Ukraine that is unreliable, but Russia and its political manipulation of Gazprom in a commercial dispute.
In fact the only reliable thing about Gazprom and Russia at the moment is their ability to predict a cold winter and engineer a gas dispute with Ukraine to coincide.
The answer may be to change the operation (but not necessarily the ownership) of Ukraine's gas transmission system, to make it more transparent and subject to European gas legislation, but that would only happen without the involvement of Gazprom.