Rethink navigation by not throwing all other content into the side drawer, try again those "oldish" tab. It will probably lift user engagement. (this will be the new "upper line" section;)
I can vividly remember helping a client to architect the experience for their new Android app when someone made the point that a hamburger (side-drawer) navigation would be a great way to simplify but also add much more content. It may not be the best idea in terms of engagement and usage.
This may not have a sole digital root alone but perhaps also a physical one. Smartphones keep getting bigger (e.g. iPhone 6/Plus). So cramming everything into a little button (that hamburger) may really just decrease engagement and usage. In fact, apart from being a Google recommendation, they want you squeeze the hamburger icon into the tiny margin at the left hand side. Autsch. Of course people oversee this.
Considering huge smartphones and small hands try to rethink navigation and whether the "old-style" tabs may not be a bigger idea. I bet Apple did quite a bit of testing before defining iOS 1.0 with tabs at the bottom.
PS: As a general point I keep on making the case that simplifying the product part rather than only the UX part of the equation is the way to go in order to achieve a truly simple product experience.