Is it possible to completely replace the application in the App Store and Google Play?

Question

Mobile development

There is a published application in the App Store and Google Play on my developer account and many users who have installed it.
It so happened that the developers of the application refused to support and develop it. Worked under the contract, studio. They don’t want to give the source code (and this is not spelled out in the contract), but it doesn’t matter.
The decision was made to hire a new team to develop the application from scratch.
Question: when the application is developed, will it be possible to replace it in the App Store and Google Play (my account) and so that users can update it without additional actions? It turns out that this will not be just a small update, but a complete update of the entire application. Will users update it or will they need to be asked to install it again?
Addition: the application is the same with the same functionality, name, etc.

Answer 1

If you imagine this as a new version of the same application , there should be no problems.

Answer 2

No substitution is possible! Just create a new version of the same application and upload a new assembly. There is no need to ask anyone to reinstall. If the user has automatic updating in the settings, then it will be automatically updated. If it's manual, it will prompt you to update your app.

Answer 3

A small update or a big one - it doesn't matter, it's important that the signatures (keys) match
I can say for sure about android: you can completely replace it, the main thing is that you have the keys and passwords for them that sign the apk for sending to the Google Play Store
About iOS: I can make mistakes, but there xcode asks to enter the developer account inside xcode, pulls out the keys from the internet, signs the finished application and sends it to the App Store. That is, in this case, you must have access to the developer account from which the application was uploaded and you can replace it.
There is a nuance with Android, if in a new application you add NEW dependencies on access to the user's phone (access to a memory card, camera, Internet, etc), then the application will not automatically update, but will require additional actions from the user - confirm consent to the new access level applications.