Days gone needs to release soon because tlou2 is so similar. If tlou2 is only 5 months after days gone, the marketing could be tight. GOW started getting its marketing push ~9 months before release ie.Well it's less a rumor than a direct quote from a Sony exec. Days Gone could come earlier, but it hasn't even had a year announced yet.
Days Gone has had a lot of raw gameplay shown if you think about it. We expect Spiderman to release first because of some rumors, but just looking at stage shows Days Gone is like a year ahead of Spiderman. I really expect it to release first because delays are not an option.