I like this very much. Although you mentioned it in the context of animation, I believe something like this could be very favorable for tech drawing, too (unfortunately it is probably beyond the scope of GSoC).
Very good point! Actually, I was trying to think about your technical proposals too, but I admit technical drawing isn't really my field, so I have trouble with proposing workflow.
All I know is that it could use a line-command system at the bottom since apparently many CAD programs have that. Though I admit, my reaction to that has always been to stare blankly. Being able to type in specific coordinates and actions though is likely something at least Some users want sooner or later...
The BIG difficulty is this: implementing sticky nodes would release a whole can of worms. Suddenly people would want: - of the stickies, one of the objects is fixed size. - or one of the objects changes size with movement. - it changes one parameter but not another. - or it maintains a certain angle - some people will bring up colours sooner or later D: - or both objects move together in a certain way (think gears, bicycle chains, and other such nasties) - eventually people will likely want 3D too - and how in the world do you assign all those properties to those poor objects?
That's a whole lot of possibilities, and it will likely put a Huge strain on the interface.
Honestly, the sooner Inkscape implements a dynamic workspace interface (that you can change according to your function: Fonts, Icons, Technical, Charts, Illustration, Animation), the sooner these things will be less of a compromise between functionality and "not cluttering the interface."
It's really nice to think of all the potential Inkscape still has, but these are some very big steps Inkscape needs to take. I admit it sounds scary. :D