To be honest, you can make draggable GLR in Avenue with different sidewalk textures based in the same fashion I am doing with the streets here. It would just take much more time and effort since it is a 2-tile wide network. Its not a far fetched idea Gaston, but it seems as though everyone who can do it right now has different projects they are working on or are in RLS.
In reality, you can do this with any set of textures! (As long as they are transit textures). Whether they have paths or not... well that is determined by the SC4Path file, and if you "forget" paths, you will have draggable textures. Now, if these textures have props on their lots, they could in effect be turned into T21 exemplars (props for netwroks to an extent). Imagine, SG canals or Jeronij's Urban Canals.... draggable. Or draggable BSC Park Paths with pedestrian traffic that actually follows paths. The possibilities are just being discovered, and it may take a long time to see them from concept to reality, but the possibilities are there.
RULs and puzzle pieces working together has just been discovered and the potential is immense. Its just unfortunate that there aren't enough of us that know enough to do it. Maybe, this will give some people the motivation to learn, because its something that will be cool!!