Harrison is in a different stage in his career than he was when he made the statements he would never play Han Solo again. His yet to be released movies have him a more supporting roll. I think that was his real problem with Han, his story was secondary to Luke. But maybe his view would be different now.
A reboot or recasting is going to happen someday. But I think it would be foolish to do that now. They should use as much of the OT cast that is available to relaunch the series while they can.