How far out are you talking? The regular Ecoboost 3.5 outsells the 5.0 and it appears to be ~$1k to go Ecoboost. Where is this insider info for us outsiders?
I've heard the possibility of a mid year 18 release, much like when the 6.2 was offered. You aren't going to find it posted anywhere, or not that I know of, It's just words from people in the industry, so I don't expect anyone that doesn't want to believe to do so.