As per a research from ICRAR, or the International Center for Radio Astronomy Research of University of Western Australia, this conclusion was drawn after making an observation of over 20,000 stars over a period of several years.
As per the observations made by around 90 scientists, smaller galaxies grow larger and extensive as stars are created from gas. As the expansion of galaxies continue, producing more stars becomes more difficult. Galaxies only have one option of fusing as well as coalescing with other galaxies.
Just by collecting gas, stars can be efficiently formed by galaxies. However, when any opportunity arrives, there is a galaxy cannibalism which involves larger neighboring galaxies.
The Milky Way has come to a point wherein stars can no longer be formed in a progressive state. It is confirmed by evidence that Milky Way has absorbed the small galaxies and this will result in 2 smaller neighboring galaxies in next 4 billion years.
These galaxies are the large and small Magellanic clouds. After these 2 smaller galaxies are eaten up by the Milky Way, the Milky Way will then be devoured by the Andromeda galaxy in next 5 billion years. The universe has its own system of survivalism. The bigger ones get to eat the weaker and smaller ones.