A few languages disappear yearly and that is not an important issue. As I believe, decreasing of the languages number may affect on culture identity, but it will make populations’ life easier.
On the one hand, a big number of people are proud of their culture, including languages. They are the most characteristical part in culture identities. Biologically, people tend to find their soulmattes and being united into the one group. In order to understand each other, they create their own signals. Moreover, those signals should be clear only for the group members, not letting enemies to get the information. For example, russian, ukraine and belarusian are three similar cultures, but the main difference is the language. By letting languages desappear, this culture uniqness may be gone.
From another hand, a presenting of a several main languages would make life easier. Nowadays, humans immigrate often and the main problem of adaptation is a misunderstanding due to the new language. A few number of leading languages may solve that problem, because of the narrowed range. For instance, it would be less complicated to complete some documents in a foreing languages.
An increasing of languages number is likely to have a bad consequences for local identities. On the opposite, this change might decrease miscommunications between people and arise personal issues with foreign languages