President of the United States- Trump
Chancellor of Germany- Merkel
President of France- Fillon
Prime Minister of the United Kingdom- May
Prime Minister of Canada- Trudeau
Prime Minister of Australia- Shorten
I already got one wrong (Fillon). I'm fairly confident about the rest (I posted this in November 2016 and Trump still will be presidentin November 2020 even if he loses in 2020). By May 2021 Trump will be gone. So:
President of the United States- Warren (ew)
Chancellor of Germany- Merkel (on her way out, presumably replaced by someone from the SPD)
President of France- Macron
Prime Minister of the United Kingdom- May
Prime Minister of Canada- Trudeau
Prime Minister of Australia- Shorten
I'll add some bonus guesses:
Prime Minister of the Netherlands: Mark Rutte
Prime Minister of Belgium: Charles Michel
Prime Minister of Denmark: Mette Frederiksen
Prime Minister of Italy: Matteo Renzi
Prime Minister of Spain: Mariano Rajoy
Prime Minister of Poland: Please let it be Grzegorz Schetyna. Please
Prime Minister of Portugal: Antonio Costa
President of the European Commission: Jyrki Katainen