This extremely long timespan assumes that the universe will continue to expand at a constant rate, eventually undergoing a “Heat Death” in which entropy will win over everything else. Something around 10^100 years for all matter in the universe to become radiation. But there is also a “Big Rip” theory that says the expansion rate will accelerate exponentially, shortening the universe’s lifespan to only around 20 billion more years. The end will also come very quickly. By the time galaxies start to be torn apart, a few years later the solar system, the Earth in a week, and in another hour atoms will fly apart due to cosmic expansion.
One of only two things will happen:
Expansion will continue until absolute zero becomes the temperature of the entire universe at which time everything falls apart. Entropy wins.
or
Expansion slows down and gravity takes hold and then everything starts to fall back down into the original gravity well and recreates the singularity at which time the Big Bang starts it all over again. Gravity wins.............