The potential threat of revolution existed in Sweden before the Bolshevik revolution; it didn't suddenly materialize in October 1917. The year 1917 was not the year of one revolution in Russia, it was a year of many attempted revolutions in Europe, one of which succeeded. Capitalists didn't need to see a successful revolution in Russia to understand that successful revolutions were a threatening possibility in many places, including in Sweden.
On the other hand, the Soviet Union did offer a concrete lesson of what could happen *if* there was a revolution -- i.e. the elimination of democracy, establishment of a dictatorship. This negative example had a real effect on many people on the left, especially in countries like Sweden where the left was deeply attached to democratic freedoms, making them *more* hesitant to support revolutionary action.
SA
^^^^^^^ CB: If all the revolutions had failed, would the capitalists in Sweden have been so likely to make such big concessions to the working class in Sweden ? In other words _didn't_ capitalists in Sweden need to see an actually successful revolution somewhere to believe that successful revolution was an actual threat in Sweden ?