What would be the use of maintaining the sanctions? In the Soviet era there were sanctions, yet they managed to clone most Western technology a few years behind. It actually helped them develop their own electronics manufacturing industry.
THere may have been some sanctions but ther eality is the USSR economy would fail if the west stopped trade with them. The USSR collapsed because their exports value collapsed in the 80s.
This is conditional on Putin remaining in power. In a world where they became a real democracy, I'd be delighted to see them as a member of the EU.