Imagine ...a "new" Reason

Simple(r) GUI, no screen wasting extra pixel padding around the essentials,

with every section at a distance of 1 click (top bar)

"pancake" style main menu when at the minimum width of the rack

(which I'll keep in these mock-up examples)

With modular sections, layout customization and all (browser included) detachable as separate windows

(to keep it simple, these mock-ups will show them all still attached)

So the Browser could still show up on the left

or on the Right, according to how it's configured

...or simply detached as a new separate window

The top bar could also include the toggle buttons for Virtual Keys and ReGroove

which both could still be detached on separate windows

or attached/stacked horizontally in any order vertically

Same with the Sequencer, could show up at the top of the Rack or still at the bottom

We could quickly toggle the Navigators with 1 click, as/if needed

same for the Transport (on all windows: Rack, Sequencer and Mixer)

...with a bigger Tap Tempo button, btw!

Any vertical oriented section could be dragged/moved/swapped horizontally

and any horizontal section could be dragged/moved vertically to any position

The Tools window could show attached on the opposite side of the Browser or detached as usual.

or, like we've seen on recent R13 screenshots, in the Clip editor section

This style of section/window hide/show/detach/attach modularity isn't new

Developers are quite used to this on modern IDEs

A simple example: Visual Studio Code

Even being able to get multiple views of the same Rack/Sequencer/Mixer

Speaking of modularity and imagining a "new" Reason...

a Modules "combinator" Rack Device would be very welcome too

Not necessarily Euro-rack "cables-at-the-front" style of modules.

Could still be Reason-style "cables-at-the-back", but different size form-factors would allow simpler rack devices to become smaller, simpler modules:

Think Kong-style modules (but probably taller).

Some Rack Extensions already "fake" it with that modular look

not quite but the look helps to imagine 

how smaller vertical modules would snap together horizontally

like horizontal rack devices snap to vertically

and in-Rack MIDI routing ?

like we've always had auto-magically-connected Audio cables that we can then reroute

that could happen with MIDI cables too, allowing "Players" to be just regular Rack Devices

Then a new class of Rack Devices could happen:

Full MIDI (not just Note msgs) processors, mergers, splitter, routers, generators, etc

...and this would finally open the way to VST that generate MIDI