I haven't used flutter yet but I also google all the time regarding the pros and cons of react native vs flutter and yes this is a good question
Differences between Ionic, React Native and flutter
Ionic is just a wrapper around Angular which uses cordova to access the mobile features like camera, microphone etc. It doesn't convert ur code into native code( java for android)
Flutter also does the same as React Native but uses dart instead.
Flutter uses widgets where as React Native uses components
Now coming to ur questions
We r comparing these 3 because these 3 can be used for developing native apps without using java for android and swift for IOS
IF u ask me React Native is better than ionic in terms of performance, fast development etc
Every framework has its pros and cons and it depends on ur project requirements
As flutter is pretty new in the market we cannot predict it. But as fuchsia is upcoming OS and google make flutter in such a way that it can make fuchsia apps too... But for present React Native is good.
Ionic as a single cannot replace. Because now Maximum companies are trying to adopt any of these three
There are no limits with Ionic
According to my practice if we have a good architecture and good practice methods it can handle everything fine