I still think Kasich would be winning if he was the nominee. Can't really predict the future, and unless the GOP significantly alters their primary schedule I can't imagine Kasich winning the nomination.
One thing I do feel confident about: Paul Ryan's career will be in the tank by early 2020. He's not built to be a Speaker, and assuming democrats retake the senate and cut the republican House lead he'll be in the same position that Boehner was in: forced to work with democrats to keep government open, raise the debt ceiling, pass some basic legislation, etc. Boehner got through in part due to his personality and experience. Ryan doesn't really have either benefit and will continue to struggle. And by late 2019 after two Clinton SC picks and various executive orders he'll have no accomplishments outside of angering the base.
(That being said I do expect Ryan to be more open to working with Clinton on some legislation. I'd expect some type of tax reform bill for instance, including lowering the corporate tax rate.).