Rise 360 is cloud-based software that has pre-designed elements (blocks), so the developer doesn't have to worry about triggers.
Studio 360, which comes with an Articulate 360 license, includes Presenter, Engage, and Quizmaker. It is a PowerPoint add-on.
- Studio was Articulate's original software. Like Rise, it is form based, i.e., interactions and quiz questions are pre-designed. You can adjust some parameters, and then just fill in the blanks. You don't have to know anything about triggers.
Storyline was created to give developers more control over what goes on a slide and how everything works. While there is some built-in functionality (e.g., the Menu, how quizzes work), you as the developer are responsible for the layouts and the programming.
So, to finally answer your question: I doubt that Articulate will ever add "iSpring-like interactions" to Storyline. (Note: I'm not an Articulate employee, so that is simply my opinion.)
However, Storyline does allow you to import Engage interactions. So if you want pre-designed "tabs/process steps/etc.," I suggest you check out Engage.