I haven’t seen Scott Eastwood break out yet. He’s good looking, smart, hasn’t been bad in anything but he hasn’t demonstrated that he’s got the kind of charisma his dad has yet, and Logan needs that.
As for X-23, I don’t think they want to create a separate series of movies set in a post Wolverine, post X-Men future.
They could just say sod the timeline issue and drop her into a rebooted universe or something, but I believe they (probably) see ‘Logan’ as it’s own little thing that did very well and maybe they’ll make more serious movies from time to time.
The real job is keeping the ‘X-Men’ movies going, one way or another.