- A UX overhaul of JOSM or Vespucci (might only be time for research and mockups within a GSoC project though)
Keep in mind that Google Summer of Code work needs to be projects with a limited scope, a chance to reach a goal in limited time and contained in a rather small part of code to actually be acceptable and usable.
JOSM (and vespucci) are mature software packages. There are hardly ever changes which fit these criteria except adding something new (new external APIs, file formats, imagery, …) Usually from principle it must be doable as external plugin. That’s also the reason why I don’t submit proposals to GSoC. It wont work for the core and plugins stuff must be mentored by people who are experts in the specific topic.
A UI rework or a mockup of this doesn’t fit the requirements. It’s not that we don’t know what can be done (we have thousands of tickets with ideas), somebody actually needs to do the work. And that usually means a longer-term contribution for non-trivial tasks.
The only idea I can think of in JOSM core would be #1981 (rotate map view) – JOSM “Rotate the MapView”. That probably could be solved in the scope of a GSoC project. If somebody finds a mentor for this…