While they may not be entirely melt in the next couple of decades, nevertheless the majority of Himalayan glaciers are indeed melting due to climate change. New data from the Indian Space Research Organization shows that 75% of the region's glaciers are retreating, on average 3.75km (2.33 miles) between 1989-2004.
ISRO examined 2,190 glaciers in total and found that, of those not in retreat, 17% are stable and 8% are advancing (Economic Times). More on Glacier Melting:
USGS Confirms Himalayan Glaciers Are Melting & Climate Change is to Blame
90% of Himalayan Glacier Melting Caused by Aerosols & Black Carbon