> The article doesn't mention any details in that regard.
The whole point here is that you don't. You have dozens or hundreds of separate apps. They can use whatever framework they want. If you want to migrate framework, you just rewrite them from scratch, without any impact to another. It solves your current problem by making it a non-issue.
Consistency comes from the design system and style guide. If you have 2 frameworks, you have to start by having multiple implementation of the style guide. As long as the implementations are accurate, the look and feel of the apps will be the same even if they use different implementations. It has to be done well though.
As for Angular 1.x/React, the solution Ive used in the past in environment that didn't have micro apps was to build tools that let me React.render arbitrary react components inside of any Angular directive, and build a React component that let me render arbitrary angular directive anywhere, so I could migrate part of apps starting at any point without affecting the rest. I unfortunately don't have the code anymore, but it wasn't very hard to do.
The whole point here is that you don't. You have dozens or hundreds of separate apps. They can use whatever framework they want. If you want to migrate framework, you just rewrite them from scratch, without any impact to another. It solves your current problem by making it a non-issue.
Consistency comes from the design system and style guide. If you have 2 frameworks, you have to start by having multiple implementation of the style guide. As long as the implementations are accurate, the look and feel of the apps will be the same even if they use different implementations. It has to be done well though.
As for Angular 1.x/React, the solution Ive used in the past in environment that didn't have micro apps was to build tools that let me React.render arbitrary react components inside of any Angular directive, and build a React component that let me render arbitrary angular directive anywhere, so I could migrate part of apps starting at any point without affecting the rest. I unfortunately don't have the code anymore, but it wasn't very hard to do.