It is difficult to say for sure but Flutter has the Future because:
- Fuchsia OS official UI Development kit as a Flutter - Fuchsia is not Linux
- Flutter Lenovo Clock integration
- Web Support
- Desktop support to build apps for Mac, Windows, Linux
- Dart & React both easy to learn
- 60FPS and more if device support
- UI is awesome as it’s truly coded in the Dart.
- Officially supported by Google Developers.
You can check out this blog on Flutter vs React Native by Intellipaat to understand better.
Also, watch this video for differences: