It's important to acknowledge that the term 'fluent' can be really problematic just because of how terribly defined it is. The CEFR model for language levels will be used for the rest of this entry just because it provides clear and useful metrics.
The Fluent Forever app that we are building is just one part of a larger platform. Beyond the pre-fabbed stuff that shows up in the first two sections of the app, the platform will facilitate interactions between tutors and students and allow them to create new material for themselves and share that material with other students. It will grow over time to include an effectively limitless amount of content for students to learn. Half of the smartphone app involves pre-fabbed materials - the pronunciation trainers and the 1875 sentence lists, through which students should be able to pretty easily reach a B1 level in their target languages in a short amount of time.
Practically speaking, with only the pre-fabbed stuff in the app, we are aiming to get people to a point where they can interact with and hold conversations with native speakers, watch TV and read books. The goal is to have users thinking entirely in their target languages during those interactions. That's going to put people miles beyond what they've experienced in the past from high school/college language courses. The other half of the app is about expanding beyond that, by browsing through student generated content and by interacting with tutors in a way that we're going to facilitate on our platform.
Those interactions are a key part of the app and platform we're developing, and will allow people to improve their languages up to any level they wish in a tremendously time efficient manner.