In the novel The Buried Age, we follow Picard for several years between his command of the Stargazer and Enterprise-D. During his life as a civilian, he works with Janeway for a while. She's a lieutenant at the time. After accepting command of the E-D he considers possible first officers, and he considers her for a while, untill realizing she's unavailable.
Nothing about that novel is canon, but it was a very good read AND the idea of Janeway and Picard as XO/CO combo is interesting.
Thanks! I'm buying this book right now. I have to admit that a Picard/Janeway team up seems a little far fetched, but Christoper L Bennett is my favorite of modern Trek writers. That alone means (IMO, of course), that it'll be good.
To the point of the actual thread, Riker would probably have died with the rest of the Drake's crew. And the larger universe ramifications of that would probably end up with Earth being assimilated by the Borg. No Riker/Shelby dynamic pushing him to take risks. No resulting "unorthodox maneuvers (by an XO so good and so experienced that he was about to turn down a third command offer)." And no time left for the rest of the Federation to mobilize and save us.
It'd actually be an interesting fanfic to see how BOBW would play out with another XO leading the Enterprise. Maybe it would end with Q's help. "Jean Luc, I'm disappointed you couldn't solve this trivial problem, but I just couldn't let you die. There's so much more I want you to see..."