Luke and Jessica are married and have a kid in the comics...so the likelihood of them ending back up together is high.
I thought it was a great series, not outstanding and clearly not outshining the "best" (like Daredevil Season 1), but it was a great build-up and a solid story. The action, while great, wasn't as well-filmed as it was in some of the other series (once again, DD Season 1 had some of the best action scenes filmed). The minor interactions between the characters and their little quirks was fantastic. I laughed when Jessica stole the beer from the guy on the subway and cracked it open...totally fits the character, and the same with Luke Cage objecting at first to blowing up the building...it fits him as he truly the most "heroic" of the characters (and hasn't "dealt" with the Hand much like Jones as he was content sticking to Harlem). Personally, I love this cast and think they've all done very well. The only guy I haven't really warmed up to is Finn Jones as Iron Fist...he still plays this "innocent, know-nothing boy" so I hope if we see an Iron Fist Season 2, we see him get a little more cocky and confident like his comic counterpart. I was hoping to see him do two iron fists as well (as in the comics, Rand plunged "both" his fists into the dragon's heart to get the power).
I liked tying the MCU Hand's origin to K'un-L'un, it helped derive Iron Fist's motivation for going after them aside from Daredevil's. Luke Cage's and Jessica Jones' reasoning was a little more skeptical, but I felt they were just more "dragged into the fold"...given Cage's attitude, I can see his reasoning for leaping in...while they did play Jones' character well with walking away from the group at first. The only thing that was weak to me was pretty much lumping in the Hand leadership for this series (aside from Madame Gao). Suddenly you have Sigourney Weaver and the Bakuto scrub from Iron Fist and these other two random dudes...
A great start to "Netflix Marvel Phase 1"
So what do we got with Phase 2? Honestly, I hope we largely see the return of Wilson Fisk/Kingpin. Fantastic character from Daredevil. Someone already mentioned Bullseye, so yes, it'd be hard to have another Daredevil series without one of his most iconic villains. For the Next DEFENDERS they could go the "Shadowland" route, but I feel that's like another "Hand" storyline, I'd personally like to see Fisk being the next "big bad", this time fully embracing his Kingpin persona.
-The Punisher Season 1 *coming soon*
-Jessica Jones Season 2 (Apparently Kilgrave will be back, but only in Jessica's and Malcolm's minds) *coming soon*
-Daredevil Season 3 *apparently confirmed*
-Iron Fist Season 2 *apparently confirmed*
Luke Cage Season 2 *apparently confirmed*
I also can't see the Punisher being a large part of the Defenders Season 2 other than perhaps a cameo episode or two. The character's violent and extreme nature towards criminals almost ALWAYS makes it tough for any team-up's he's had (other than with like-minded heroes...like Wolverine). Aside from Daredevil, I could certainly see the Punisher butting heads BIG-TIME with Luke Cage. Jessica Jones might actually like him cause he's a big a-hole like her.