Our space-ward expansion has some hard physics limits. And we've not yet eclipsed what was already done decades ago. And even settling Mars will require more sustainable lifestyles than most first world citizens now enjoy.
There is less low hanging fruit as things progress. I'd guess we're very close to the peak of attainable technology.
Once sustainability comes into the picture then, IMO, we're beyond the limit.
Not many people, and pretty much no research scientist, would agree with that statement. I can personally think of several technologies I'm 100% certain will exist in < 40 years that will drastically alter everything about day to day life.
Not if they decide to use nuclear power. Humanity has at least one more dramatic jump in power-use/person that has been ready since the 1960's.