We ignore technological advances at our own peril. For example what was "easy oil" 20 or 30 years ago contrasted with "hard oil" (bottom of oceans, etc.) may now be easy. Will it be "easy" 20 or 30 years from now? But let's go deeper into what we mean by "easy" and "hard".
Does easy mean plentiful and shallow? And simple to extract? The oil fields in Texas, Oklahoma and Pennsylvania are by definition easy. They're shallow and (if I recall correctly) the initial find in PA was a drill for water, not oil! Yes, much of that might be found and extracted. However at least some of the planet has not yet been explored for mapping, let alone natural resources.
I read today about White Hydrogen. This could be the next fossil fuel and be totally clean. This White Hydrogen was found as they were drilling test fields for oil. Sound familiar?
As for the "hard" oil becoming "easy". It could happen. And somehow the "easy" oil keeps producing long after they were scheduled to run out according to projections that are now overcome by events.
The future holds many opportunities framed as challenges today. Stay tuned, it's about to get even more interesting!