As far as I can tell, it means a landscape of languages: how languages vary over geography.
"Refugeeism may weaken the demographic strengths of some languages, while it is also doubtful that new, lasting linguistic diasporas will emerge that are comparable to those of imperial European languages today. The real impact of refugeeism will depend on whether or not the refugees, most of whom relocate to neighboring territories, will assimilate to population structures of their host countries, if they remain there permanently. This factor will determine whether the linguascape of Africa, for example, will change."
- Salikoko Mufwene, "Future Tense: Languages", Fall 2015 The University of Chicago Magazine (http://mag.uchicago.edu/university-news/future-tense#languages)