Very simplified answer

After Jigsaw, public will be public only within the JAR scope. To see the class outside the JAR it must be exported.

Java will force modularization because any inter module interaction will have to be specified in the module-info file.

For example, if you produce a WAR it will remain almost unchanged but all JARs packages in the WAR must define a module-info (or not define it and be treated as automatic or unnamed modules).

Maven has 2 main features: dependency management and building:

• Dependency management means Maven can determine versions of libraries
  and download them from repositiories.
• Building means Maven can compile code and package it into artifacts.

To conclude: Maven will still be responsible for building, but one must learn how to compile and package using Jigsaw modules.