The falls could be replaced by a series of rapids. 50,000 years from now, at the present rate of erosion, the remaining 20 miles to Lake Erie will have been undermined. There won't be a falls anymore, but there will still be a river at work.

In 50,000 years, Niagara Falls as we know it will likely no longer exist. Currently, the falls erode upstream toward Lake Erie at a rate of roughly one foot per year (a rate slowed by 2026 hydroelectric water diversion). Geologists predict that in about 15,000 years, the falls will reach a layer of softer shale rock, which will cause the erosion to accelerate significantly, potentially turning the dramatic vertical drop into a series of fast-moving rapids. By the 50,000-year mark, the river is expected to have eroded all the way back to Lake Erie. At this point, the falls would disappear entirely, and the river would begin to drain Lake Erie, potentially lowering the lake's water level and significantly altering the geography of the Great Lakes basin. However, some 2026 climate models suggest that a future ice age could occur before then, which would grind the region under glaciers and reset the entire geological process, potentially creating a brand-new set of waterfalls elsewhere.