Science is always an iterative process. We know more now then we did 10, 50 or 100 years ago. In 1920 We did not know if our galaxy was all of the universe or how far away the “Spiral Nebula” were (We now call them galaxies). Edwin Hubble (for whom the telescope is named) first measured the distance to the Andromeda galaxy (M31) in the mid 20’s. In the 1940’s we did not really understand the nature of our own galaxy until Walter Bade worked it out with the 200″ telescope at Mt Wilson. We didn’t understand the rotation of Galaxies until Vera Rubin proposed dark matter.
Yes in the future we will know more than what we know now. However that does not mean that most of what we now think to be true will be discarded. It simply means that the knowledge that we have now is always at best an approximation to the truth. As what we know increases our ability to understand how it all fits together also increases.
50 years from now I assure you the universe will still be expanding and galaxies clusters will still be bound by gravity, we just might know where that gravity comes from. While now all we can say is that it is “Cold Dark matter”. And yes there is some math here, but none of what I have been talking about requires math to understand (at least at this level).