"Some decades" ? Last time I checked, Laherrere predicted peak conventional + unconventional for 2019 ? (There's always the political uncertainties of course, especially in the Middle East!)
"The main conclusion of this study is this from 2018:
-only 6 countries have not yet reached peak: Brazil, Canada oilsands, Kazakhstan, Iraq, UAE,
Venezuela Orinoco
-19 countries (out of 35) have or will have a decline rate of 5 %/a
It means that, excluding the 6 countries before peak, the best and the simplest way to forecast
future production is to decrease present production by 5 % per year"
"6 countries have not yet reached peak" and "excluding the 6 countries" surely doesn't sound like "peak" everywhere.
So yes, it seems that, at longest, in "some" decades the global peak will do happen. Laherrere also documents why the exact predictions are hard (see all the graphs there).
My point is more, whoever thinks that "scientists will always find something" surely thinks in short enough frames. There is a finite amount of fossil fuel material on Earth.