I assume they will roll another one out in a few years, I think everyone who buys a small phone hangs on to it for a long time. Before I bought a 13 mini my previous phone was the original SE (also small) so obviously I'm not upgrading every year.
It was 4 years between the original SE and the 12 mini, they released the 13 mini right away but I think that might have been because battery issues with the 12. Maybe the ghost of Steve Jobs begins to haunt Cupertino after a few years of Apple not releasing a smaller phone