You also need to consider what the things inside it look like to you or anyone else. The observable universe is the volume inside which light can reach us here on the earth… technically it’s different for everyone because we’re all in a slightly different position, making everyone the centre of the universe, but in terms of the scale of the universe, that’s irrelevant levels of accuracy and you can safely state that everyone on earth is in the same place. Now because space is expanding and carrying stars and galaxies with it, those galaxies will eventually pass the point where their light could travel for an infinite time and never reach us, in other words, they would pass beyond the edge of our observable universe. Eventually, given enough time, all that will be left in the night sky (long after the earth is destroyed) will be our galaxy, and possibly bits of our local group, which are gravitationally bound and would hold their relative positions as space expands around them.