In Picard's Nexus fantasy, just fade out during Guinan's line "I can't leave here. I'm there already, remember?" Then Picard finds himself back on the planet. The implication is that Guinan somehow sent him back, which I think is better than the unexplained return in GEN proper.
Really? I'd find it immensely jarring and unsatisfying for Picard to just reappear on the planet after being in the Nexus for all of ten minutes, and not even remotely influenced by its lure.
I was actually thinking about this last night, in bed (what? isn't that a perfectly normal place to think about Star Trek?)
First of all, I'd have to rewatch GEN to get a better idea of whether it would or wouldn't work, but I suspect that removing the Kirk section would have the effect of increasing the thematic importance of Picard's Nexus experience. As it is, the importance of this fantasy in relation to his traumatic loss of his family is forgotten thanks to the prominence of the Kirk section.
I also thought about how to add weight to the transition back to Veridian III. Instead of the echoey fade which was the first idea that occurred to me, how about a gradual whitening of the screen accompanied by a sound effect, as Picard looks about disoriented. Then the whiteness and sound fade, and we hear a final line from Guinan as Picard finds himself back on the planet.
What that line would be, I don't know. The editor would have to search the Guinan episodes of TNG for something appropriate, but maybe something about how Picard is stronger even than she thought he was, or how he is a man with things still left to do. She tended to speak in homilies, so there's probably a lot of choice