From what I've been able to discern, OSM's road data is reasonably complete. Place data perhaps not as much. Is that the gap that you foresee additional contributors filling?
Road data is largely complete in Western Europe and getting there in Eastern Europe. In much of the US, it's still raw USGS TIGER data, which is very low quality and needs fixing. Asia, South America etc. are much patchier.
Address coverage is almost universally poor.
POI coverage is patchy: landmarks are often well surveyed, businesses less so.
Comments
How many contributors does OpenStreetMap need?
From what I've been able to discern, OSM's road data is reasonably complete. Place data perhaps not as much. Is that the gap that you foresee additional contributors filling?
Road data is largely complete in Western Europe and getting there in Eastern Europe. In much of the US, it's still raw USGS TIGER data, which is very low quality and needs fixing. Asia, South America etc. are much patchier.
Address coverage is almost universally poor.
POI coverage is patchy: landmarks are often well surveyed, businesses less so.