The link shows (just eyeballing the plot) about 80% of the earth's land area being fairly uniformly distributed between 0 and 1000m above sea level. If we assume (a bit too simply, but it probably isn't very far off) that a 10m rise in sea level will simply turn everything between 0 and 10m above sea level into no-longer-land, that suggests about (10m/1000m)*80% ~= 0.8% of the land would go away. Doesn't seem too far out.

(How bad is the oversimplification mentioned above? It's too pessimistic because some land below sea level might remain usable, as with the Netherlands. It's too optimistic because some land still above sea level might become much less usable, e.g. by turning into little islands. My guess is that both these effects are quite small and they're similar in size.)