Since non-Hindu people in Nepal were used to with not killing the cows for past decades or centuries, even if Nepal allows killing cows in the days to come, even non-Hindu people will not be comfortable doing that in Nepal. It's like being a Nepali or growing up in a Nepali culture and ethics, most of the Nepali Muslim eat non-Halal meat especially when Halal meat is not easily available. So, culture or tradition we have over a time has a great infulence on what a whole country does or what people do. Perhaps killing of cows should be continued to be banned to respect the sentiment of mejority of people in Nepal because most of the Hindu Nepalese will not comfortable or happy watching non-Hindu brothers killing cows and non-Hindu people surroundered by thier Hindu brothers will not be comfortable either killing cows and eating beef in Nepali culture at least for another 20 years until when many Hindu Nepalese outside Nepal, not all, who eat beef now go back to Nepal and change the culture or feeling of common people towards it.