I read a bunch of these threads, and while FTP isn’t the sole determinant, I think I came to the conclusion that while 4 w/Kg at sea level was certainly possible, I’d feel better at about 4.2 w/Kg. (Lots of factors will go into it: TTE / Endurance, Pacing & Strategy, Fueling and Hydration, Total System Weight & Efficiency, Weather & Luck, etc. )
Can’t remember if I posted it above, but there’s some good info in this thread about NP w/Kg and finishing times.