It's not an issue of if the Himalayas would stop rising, but when. Articles of the past months have said that the range would stop rising in the best guess of 20 million years, not because of gravity, but because of how the mantle influences the movements of the landmasses.

But what the articles never say is what would happen when the Himalayas stop rising in the distant future. How would the topography of Asia be affected? How would Tibet react?

Glaciers and snow topped mountains are already in rapid decline because of global warming. The ice will certainly be long-gone by the time the tectonic conveyor belt grinds to a halt.

The eroded debris will drain into the Bay of Bengal. The current effects of rising sea level will flood most of Bangladesh in the short term, but it will ultimately be reformed as erosion overtakes rising sea level.

As for Tibet, one would expect a long period of erosion, mainly by deeply incised rivers dissecting the plateau, much as the Colorado River is cutting away at the Colorado plateau in North America; a process greatly aided by much increased rainfall.