For me I always said the best news would be no more offspring... I really felt like I had to push back against what the EU overdidbut I figured if the line was to continue Leia and Han were always the most likely avenue. I felt like Luke sort of transcended the sexual while that was more the domain established on-screen of Han and Leia. And if you're giving big roles (or in the case of Han, a reportedly 'gigantic' or a lead one) to the family, it follows that a new addition to the family would be focused upon... for good or ill.
The next best news is if there's only one and it's Leia and Han's. Double plus good for a girl, because I think there is better story telling potential here with a Mother-Daughter and Father-Daughter story... because the PT was also about a Mother-Son relationship and the OT was also about a Father-Son relationship. Will Adam Driver or another factor into this new equation? Remains to be seen if this conflict does come to be revealed as sister against brother though that would make two. Does the son somehow kill the father? Some foundation for storytelling here if they go that way. But it's all premature--my writing about it, because it could be very different. It's possible certain things will have to wait until Episode VIII or IX to be revealed if at all because it's scripted in a different direction.
But a female character with some Han Solo attributes of the Skywalker bloodline that will likely eventually swing a lightsaber? I think that could really work...by being the polar opposite of how we last saw Padme in Episode III. Episode I Padme ain't a terrible character, or at least on paper she's not. By Episode III that was a terrible character, and serves as an instruction manual as to how not to write the female lead in a big action movie. I get Lucas wanted to show where Luke and Leia get their fundamental goodness from but it's just not very interesting. Lucasfilm and everyone involved owes it to Star Wars fans and foes to deliver a more modern female character, this time as the trilogy's protagonist.
If you want your protagonist to be like Katniss or Korra or an "extremely gymnastic" character, having it also come from Han Solo's line as well as the Skywalkers makes just more sense than Luke's in a certain sort of way, especially since we never saw him in a relationship with anybody, or anybody like that.