It all depends on how you define success in your winemaking. If you want something that is "drinkable," it probably would last, that is not spoil, for a year or two at 70 degrees or slightly more. I agree with Wade, that protection from light and vibration are important, but I respectfully disagree with the statement that "stable temperatures are more important than the temp itself."
Both are very important and for different reasons. Temperature fluctuations cause the wine to expand and contract in the bottle forcinggasses out and pulling air into the bottle. Higher temperatures "cook" the wine to an extent but more importantly do not allow it to develop as it would under more a ideal temperature, i.e. 55 degree F.
The up side of this is that not allowing the wine to develop, you will never know that it could have been better. This is also the down side.