Is this a serious question?
Kallis has over 100 Test matches compared to 16 from Hussey and Kallis is younger as well
Hussey has a brilliant average but 16 Tests is no basis for drawing any conclusions. It isnt a large enough sample size to sugest it will continue.
In fact there is more evidence to suggest it will decline. Consider after 32 ODIs Hussey averaged over 100, yet now after 72 games it has almost halfed to 58.
As good a player as Hussey is, a freak average over a small number of games doesnt prove anything.