I am wondering if the next version of Ionic (v4?) will be able to handle React instead of just Angular ?
I would say yes
According their blog post http://blog.ionicframework.com/ionic-2017-18-roadmap/ Ionic4 will be framework agnostic
Ionic 4 is significant for a few reasons, but primarily because it’s the first release of Ionic that will be framework agnostic.
You could even probably already try the beta I guess