Russia's agricultural sector is only a 4 pot with over 25% of land cultivated in Soviet times, no longer so, where roads and infrastructure have been ignored outside of Putin's main supports area of Western Russia (hence a rise in nationalism stoked, by Russian adventurism in Ukraine (Don't ask about the Siberian nationalist rally on 17th August, some of the Russian press had to hastily remove articles on this and have been officially sanctioned
)) and are no longer reachable. A shortage of finance means that cultivation is only running on 2 cylinders through lack of investment, hence the need to import 20-60% of different foods with an average of 48%, so no pressure then from banning western food producers.
Could their struggling agricultural sector pull the skin of a rice pudding, like a struggling Omega 4 pot, no there is no rice pudding.
Soviet nostalgia is generally limited to the oldest Russian and Russian satellite country's generation, especially women. I'm sure they will thrilled at the queuing for food for what little supplies are available. Soviets seem to think that queuing is an efficient use of a countries productive time.
2014:
Pre 1991:
Yes, there will be some substitution, but food can not suddenly be magicked from somewhere it takes time to grow, so in countries which make up the shortfall, their prices will go up, they will also go up in Russia, which already has major inflation problems with falling real wages, so this will disproportionately affect the poor. There is talk of price caps on essential foods, which will guarantee their disappearance, as producers won't produce at a loss nor will shops sell.
As one Russian wag said: The bad new is that with no food in the shops, so we will have to eat sh*t, the good news is that we have plenty of sh*t.
A Ukrainian wag: We will be back to Russian tourists doing food runs to Ukraine or Russian locusts as they will be called.
(They will join the Colorado's in East Ukraine which is what the Ukrainians call the Russian Terrorists there with their St George's ribbons after the stripped shells of Colorado beetles.
I don't think Putin has many toes left from where he keeps shooting himself in the foot. His actions over the last 9 months have been highly irrational at a tactical and strategic level and what is meant to be a strategy to keep Putin in power is increasing his chances of demise, which IMO can't happen soon enough, providing it is a peaceful transition where in my view Putin will push the nuclear button if he thinks it will keep him in power longer (Many Russians view with their extensive shelters a nuclear exchange winnable).