Life will ultimately run out of resources on earth or even our solar system. At that point we will need to go outside our solar system and galaxy to find new resources.
We can’t make use of an almost infinite universe. Even if we could travel close to the speed of light, we could only access 2% of the universe. By the time we come close to the rest, it will start traveling at faster than the speed of light and become forever out of reach. Although we are limited by the speed of light, space has no limitation to how fast it can expand.
The best option we’ve had so far for reaching close to the speed of light is a solar sail. A giant ultra light sail that harnesses the energy of solar powered lazers.
Even if we settle far off worlds, if the current expansion continues, we will drift so far apart that our communication will be patchy at best. The only way around this would be in building stable wormholes. But we have yet to come close to finding or understanding anti matter that’s required to create these.
No matter how far we spread or how good our communication becomes, we will face the natural decay of the universe. The estimates for the amount of time the universe has left range from 10 billion years to hundreds of billion years, depending on how the effects of dark matter play out.
If dark matter continues at it’s current pace, the universe will expand indefinitely until stars die out and all matter gets reduced to black holes.
If dark matter reverses it’s current pattern and starts contracting, we could end up in a reverse big band with the universe condensing down to nothing.
If dark matter or the universe itself reacts in an unexpected way to an ever expanding universe. Everything we know has limits, there is no reason why the universe should be limitless. Once we reach these limits, we could see all matter fall apart, or large zones of destruction appear.