As Dennis Meadows himself has said a number of times, there is no "prediction". I'ts like predicting temperature in the future based on CO2 levels. A bunch of stuff has to come about to allow the emissions to occur. It's a likely projction if a bunch of inputs are met.
That said, it was a ground breaking study, something President Jimmy Carter took seriously, and what got me interested in this whole thing in the early 1990's.
Alas the US and the world ignored the information (worse still laughed at it) and decided to keep eating the future and shitting in our own nest ... And here we are, "On the eve of destruction "