When the clock ticks over to the year 2100, and 3/4 of the population on the planet speaks Esperanto because of this Duolingo course, this sentence will be somewhat outdated.
I also assume that we will be on tree version 42.0 by that time and the course contributors for the tree version 1.0 will have been elevated to god-like status.
The year 2100 is the last year in the 21st century. It won't be outdated until 2101.
I answered "it is the twenty-first century" because I thought it borrowed from french the way one says "Nous sommes lundi" ou "Nous sommes en janvier" to mean "it is monday" and "it is January", when what is literally being said is "we are monday" and "we are in January."
En Esperanto, cxu ni povas ankaux diri "Ni estas lundo" kiam oni signifas en la anglan "It is Monday"?
Dudek-unua Jarcento Skizoida Viro: