The role of government in society is one such "evitable" or uncertain aspect of the 21st century. Approaches to the new century already diverge among such entities as Canada, the U.S. and the European Union.
The phrase "inevitable becomes evitable" is from F. Scott Fitzgerald's Tender is the Night.
So far in the new century we have been experiencing those things that are inevitable for all post-industrial societies: telework, knowledge workers, trains, decline of suburbs, etc.
But now each nation has to make decisions- - and those decisions can well determine the nation's future prosperity and well being in this century- - that are not inevitable.