Well, the Fantastic Four rights aren't reverting to Marvel, so I'd say the answer is no. As recently as last November Marvel President Kevin Feige called the idea of getting the F4 rights back "an impossibility at this juncture". As far as I know, nothing has changed on that front in the past 6 months.
As far as Lee's cameo, it's possible that he was a Fed-EX agent more than once in his "career" -- if a disguise works well enough, why not keep using it? Even if he was talking about Civil War, Marvel's Easter Eggs rarely follow their canon timeline as much as they should, and often get sloppily ret-conned away later -- the "totally not Adam Warlock's cocoon" from Guardians vol. 1, or Stephen Strange discussing a case about "totally not Rhodes" accident are two other examples. If pressed, Marvel will probably do the same with Lee's comment.
UPDATE: Marvel has done the same with Lee's comment:
And Stan Lee in the movie says, ‘That time I was the Fed Ex guy,’ which is what he is in Civil War. I screwed up; I wasn’t thinking, But I’m going to say that probably Stan Lee used the guise of a Fed Ex guy more than one time.
As far as The Watcher's go, while they did appear in a Fantastic Four series for the first time, that doesn't mean much. F4 is Marvel's oldest comic series. Lots of things appeared there for the first time, but migrated out to become their own thing. When Marvel signed their deal giving Fox rights to the F4 team, they got to pick and choose what did and didn't go with it. Obviously Fox is going to get as much as they can, so they got classic F4 villains like Doom and Silver Surfer, but they didn't get everyone who's ever been in an F4 story. (Namor, for example, is very closely tied up with Reed and Sue's life, but AFAIK Marvel still holds his rights). Uatu has appeared in all kinds of series, including Guardians of the Galaxy, the "Civil War" storyline, and the "Infinity Gauntlet" storyline. It's unlikely that Marvel would have signed over his rights to Fox as part of the F4 deal.