I can not say that building wall help in economy of Nepal, but definitely VISA systems might controlled Indian population migration and all kinds of serious crimes like human trafficking, black marketing, smuggling and illegal activities. If 1 Nepalese migrate to India, 1,000 Indian migrate to Nepal. That is the worest population crisis as well as it creates all kind of political and social problem in Nepal. Tommorrow, Indian population will get Nepali citizenships and build majority votes. Then Indian people will be minister and prime-minister like Fiji and Morisos. Nepal might include into India. Who knows that future?