It looks like an economic war, but i can be something bigger - the end of the global economy as we know it.
It doesn't work that way. GDP matters if there's a global hot war with massive casualties — how many tanks, traiers, cannons, guns and ammo can you produce, how many ammo can you afford to shoot in every attack and so on.
You probably should calculate GDP per capita and keep in mind that there're a lot of countries that would be happy to take place on russian market - China, India, Turkey, Latin America etc.
One thing should be clear - Putin is very western-oriented person. He's not willing to give away everything for just words of friendship and support as his predecessors did, but he wants Russia to be a part of the western world. Demarche like this is very uncharacteristic for him. It not pure populism - I'm sure.
There were economic relationships with Germany before WWII (technologies in exchage for resources mainly) and with allies during the war. But after the Cold war had begun relationships stopped. Only with the Warsaw pact countries.