Barring injury:
Federer will win at least one Slam - most probably AO. As things stand today, who will defeat him there? Nadal? Sure!!!!!
Since Wimbledon falls almost on his 37th birthday, it may not be as much of a Slam dunk as AO. Still winning two Slams is quite probable. Maybe even possible.
Nadal will win two Slams. FO? USO? If Federer falters @ AO, Nadal may step in to complete the second Career Slam piece. If he does, he may STILL end the season with just two Slams (Nothing @ USO then). Worse case scenario? Just FO.
This back and forth between Federer and Nadal (Federer winning just enough to deny Nadal gaining ground on the Slam pole) will end in 2018 leaving Nadal to then 'employ paper cuts' (winning one Slam per season @ 2019 and beyond) to close the gap.
Federer will win two Masters 1000 titles.
Nadal will win three Masters 1000 titles.
Djokovic will win one Masters 1000 title.
Nadal will be the year-end No. 1.