I don't think so. I am of the opinion that the USSR's demise came as a result of runaway military spending (10% of Soviet GNP, in Gorbachev's time), in a nation far too small (in population and capital) to afford it.
Soviet military spending was not "run away". It actually stayed pretty stable over the 70s and 80s (after declining after Stalin died).
Gorbachev used military spending as an excuse for the Soviet Unions economic problems because he could blame that on the West (i.e., they make us spend all this money to defend us, this is why you can't have nice things). It allowed Gorby to downplay the systemic factors behind Soviet economic troubles and avoid admitting to the public that the economic planners had just made plain wrong investment choices.
The impact of the Great Patriotic War on their demographics, and by extension their economy, should not be neglected. Unlike the West, they could not (or refused to) make up their low birth rate with immigration.
The Soviet birthrate was low for a country at its level of development, but it was higher than that of the USA for most of its history. It only declined badly when the economy imploded in the 90s.
Wouldn't the Union still implode for economic and structural reasons, though?
A Soviet Union that avoids the enormous costs and destruction of WW2 can spend those resources on growth and improving itself.
A Soviet Union that hasn't fought WW2 has a far higher population - about 400 million people by the 90s. More labour to throw at the economic problems of the Union means more time to turn the ship around.
Importantly, the Soviet Union hasn't lost most of the potential talent of the post-revolutionary generation. That in turn means they can maybe imagine a Socialist system that isn't Stalinism for the USSR in time before Stalinism inevitably hits the wall.
And not having the empire in Eastern Europe probably helps enormously. Eastern Europe was a net drain on Soviet resources and undermined Soviet political stability both when it did well and when it did badly since BOTH discredited the USSR in the eyes of Soviet intellectuals.
As such, I'd say Soviet collapse was much less likely without WW2.
fasquardon