Over time all lakes will shrink and disappear. Some will dry out, others will fill up with sediment. This doesn't happen overnight. The Earth is constantly shifting and moving. Lots of the world's lakes formed because of changes in the land caused by earthquakes.
Earthquakes sometimes leave basins in the earth that become lakes.
Many lakes in the western United States, like Lake Tahoe on the California-Nevada border, were formed in depressions formed by earthquakes. Other changes in the Earth happened more gradually. At one time the ocean covered parts of the Earth that are now dry land. The ocean floor lifted in some areas and dried out. Sometimes large bodies of water were cut off from the rest of the ocean.