1. "n = 1" is misleading. In a time series, the n is the number of time samples; thus n is large here, not 1. Moreover, every year provides another opportunity to test Hubbert's model, and every year U. S. oil production provides further data that is consistent with the model. --Yes, despite all the political and economic pressure for the U. S. to become "energy independent", despite all the tax breaks to oil companies to subsidize domestic oil production, despite all the gee-whiz new technology to exploit existing oil fields and find new oil fields, U. S. oil production continues to drop, just as Hubbert predicted.
2. Hubbert's model also fits oil production patterns fairly well in other oil-producing nations like the UK and Norway. Sure, we need further research, but there is in fact a growing body of data that empirically validates the regression model.
Miles