Lucas would never have collaborated like JJ did. So no Kasden. He couldn’t have gotten the performance out of Harrison Ford that JJ did.
What performance? Harrison was rather at his average in TFA. Even in ROTJ, when he obviously didn’t want to try too hard, he seems amazing compared to TFA.
I found Harrison Ford to have put in a better performance in TFA than he has done in a long time, certainly better than Crystal Skull. It was Han Solo, not grumbly old Ford like so many of his recent performances.
Lucas might have convinced him to come back via the method of “truckload of money”, but Harrison would have half-assed it. Of course Lucas would have half-assed it as well so it would be consistent.
I remember reading back in 2007 that George had offered Harrison close to $40,000,000 to do Episode VII. Harrison’s response was something like, ‘There’s no way in hell I’m going to let you put me back in that cockpit with Chewbacca again!’ Harrison was excited to do TFA because he thought the script was great and Disney hired the right people to do the movie, and it showed in his performance.