The cool thing about scientific and engineering progress is that we can't know what we will discover and develop. 200 years ago, we started having electric lamps. In just 100 years time, we have gone from computers being fringe and folly to them being integrated into places they don't even need to be for sheer convenience. Assuming humanity makes it another 100 years and continues to advance technologically, things we only dream of today could easily be so common-place that people can't imagine living in the current dark-ages of technology.
Also, 100 years is a cosmic blip! If we are thinking ahead to the point where we can't see things in the universe that we can see today, humanity itself will likely not be recognizable from our current vantage point... assuming it exists at all.
Outside of our observable universe is probably just more universe. We're stuck in a bubble within that universe due to the speed of light and cosmic expansion. The expansion of the universe is accelerating and that expansion continually pushes more of the universe outside of our local bubble. Relative to our reference point, some parts of the universe are moving away faster than the speed of light.
Supposing you had some sort of mechanism to travel across the entire universe, when you get to what we on Earth would see as the 'edge' of the observable universe, you could see past the boundary to another section of the universe as big as this one. If you could communicate back to earth, you'd effectively increase the size of our observable universe by half.
But while we're still trapped by the speed of light, we can never see beyond the edge of the universe. An edge which grows closer and closer, faster and faster with every passing second.
No matter how big your sensor is, you can't detect photons that don't exist. Once an object passes beyond the boundary of our observable universe, it effectively ceases to exist for us. No photon from that object will ever reach us again.
Based on today a knowledge of the universe, even if humans colonize the entire universe, you would eventually lose contact with humans in certain areas and therefore their knowledge.
I felt like humans were doomed after watching it, despite the vast scales discussed.
By that same coin, the universe going dark is the most depressing and crushing.
Let's hope our feeble understanding of the universe yields to a future full of more possibility than we can imagine today.