It's not a matter of if it's a matter of when!
Every new initiative will add more complexity and work/time to the already existing legacy code that we have, witch will result in wasted money.
Migrate all at once and stop the heavy development on the front end part. This means we can still do small things and adapt them in the update as well.
This is the right way because we can also get rid of the unwanted things that gathered along the way.
Going to a hybrid state:
Conflicts that can't be predicted at this moment.
Much of the development environment and tool builds must be reviewed
The code becomes necessarily heavier because 2 different frameworks are loaded.