Path of Exile Act 5 was recently confirmed to launch in 2017. It is assumed the act will launch in Spring or Summer 2017.
Although the new challenge leagues will start in December and only last 3 months, GGG had around 3-4 months of downtime between Talisman leagues and 2.0. During that downtime they had events such as a One-month Race.
Act Five will shorten the game into 2 difficulties (down from three) and make it 10 acts long before endgame.
Lastly, I apologize for the lack of content recently but it will definitely be pumped up in the coming days. Check back daily!