Though your optimism is commendable, coming 3rd in GDP would require overtaking both India (with its 1.1bn people now moving into full-scale industrialization) and Japan (which is already a fully-developed and very technologically advanced nation) – which I don’t see happening by 2020.

Overtaking Japan may be just about possible by the 2020′s given that Japan is burdened with a rapidly aging population which is predicted to fall at an accelerating pace from now on, which dooms it to long-term economic stagnation (its dependence on foreign energy imports is also going to be increasingly risky in a post-peak oil world, and it would probably have to re-militarize – canceling out the economic advantages of its old pacifism). However, I don’t see Russia overtaking India any time soon and expect the relative gap between them to continue growing, especially after 2020. It would take some kind of Indian subsistence crisis or collapse to reverse these trends, which is admittedly a real possibility by the 2030′s due to depleting fossil aquifers and melting Himalayan icecaps barring major technological or geo-engineering breakthroughs.

#1 or 2 Agricultural exporter – if Russian agriculture grows at 6% a year it will pass the USA as the biggest exporter by 2020 6% is a reasonable if not conservative estimate.
largest car manufacturing center in Europe
#1 in nuclear reactor production
#1 in nuclear fuel
global player in civil aviation with superjet 100 and ms-21
#1 military hardware exporter
#2 oil producer
#1 gas producer.
It center
logistics and transport powerhouse

I give Russia an outside chance at the 3 spot with the 5 spot a lock.