In the 20th century, a strong increase in IQ test values was observed. However, the results of the last few decades point to an end to the FLynn effect or even its reversal. Scientists came to skeptical assumptions for the 21st century. There is hardly any research on the possible future development of intelligence. Here we present a statistical approach: Results from 24 student achievement surveys (TIMSS, PISA, PIRLS) from 1995 to 2019 serve as the data basis. In order to be included in the analysis, at least five measurements per country had to be available (N = 79 countries). For statistical estimation, trends (calculated via subtractions between measurements within one student survey approach), linear regressions and nonlinear quadratic regressions (both using any given student achievement data) were applied. A correction for outliers smoothed the results. For the sample of 79 countries, IQs would increase by about 10 IQ points by 2100 (international mean IQ 101). We compare the results with results from theoretical models. The theoretical models came to less optimistic conclusions. The results depend on the selected statistical (e.g., linear or nonlinear, outlier correction or not) and theoretical assumptions. We recommend that also other authors address this research question.