Third Party underperformed this year, Call of Duty, Watch Dogs 2, Titanfall 2... Third Party and First Party is going to be much bigger next year. You say the lineup is going to similair... but what Title did Sony have for Holiday 2016? The Last Guaridan, can't think of any other exclusive and that's certainly not a system seller.
Horizon, Gran Turismo and maybe God of War, along with a cheaper price and the first real deals on Pro consoles and a stronger year for Third Party is going to be the key for increasing YoY in 2017.
You're assuming third parties won't underperform again this year. When third party titles are falling flat so consistently, it seems indicative of a pattern among that style of games. It's quite possible that third party games will continue to decline. Aside from Red Dead 2, which third party games do you expect to provide a big sales boost?
Plus, at this point there is a limited amount that any individual title can do. The kind of person who is going to be into something like God of War is also the kind of person who would likely be into Uncharted, Infamous, Assassin's Creed and the like. There may be some people for whom God of War is the straw that breaks the camel's back, but the later any title releases in a console's lifespan, the less impact it's going to have.