I don’t think this is a minor case, and I don’t think it’s limited to urban environments.
PS The null option is quite real, I think: Nothing, it’s fine as it is, just add proper physical characteristics.
And: null option, but add a proper foot scale or foot grade.
Good point. I removed the mention of “minor” and “urban”.
I was thinking it would be good to document pros and cons for each option, otherwise it doesn’t really matter which option is it, so long as the majority agrees that this is the way to map certain features.
I’ve created a thread for the issues:
Yours seem like a decent summary of proposed ways forward. So, the only thing I see missing is the list of arguments/concerns for each of these options. Then we could focus on addressing those and, finally, vote for the best option. Or at least the least bad one.
Indeed, and beyond that, it’s a well accepted technical term.
“Crib Goch is a fantastic grade 1 scramble along a knife edge ridge in Snowdonia, Wales. It is probably one of the best scrambles in the United Kingdom, offering excitement to scramblers of all abilities.”
“A grade 1 scramble is essentially an exposed walking route that takes an interesting route or line up a gully, ridge, or buttress that will require the use of your hands to climb over the steeper sections.”
(About 15 years ago we went walking in North Wales. There was a particular walking guidebook we’d very much appreciated in South Wales, so we bought the volume in the same series for North Wales. We had previously found the “moderate/challenging” walks in the South Wales guidebook were very doable, so we picked a “moderate/challenging” walk from the North Wales guidebook. Oh boy. Turns out the grades were not comparable between the two books. It was not a bundle of laughs. Returning to work the next week I told a hill-walking colleague where we’d been. He just looked at me and said “Yeah, you do realise Tryfan is a grade 1 scramble, right?” I think my answer was “Well I do now…”)
None of the above.
Concentrate on the acheiveable -
Ensure that downright silly usecases such as “scuba paths” are changed to something more fitting (in this case, not a highway tag).
On a community by community basis, change appropriate high difficulty ones to highway=scramble. While doing this explain to the local community what is happening and also keep data consumers informed.
When people add new highway=path without any idea of what transport modes are catered for, explain the issue to them.
When people add new highway=path without a surface tag, explain the problem to them and encourage them to supply the missing information.
Look for existing highway=path near you, survey, and add any missing tags.
Can you explain how this will function practicaly? Who will explain, how and when?
Anyone who wants to be part of the solution 
OSM has always worked on a “ground up” trajectory rather than a “top down” one. That applies pretty much across the board, whether it’s helping new HOT mappers square buildings, or explaining to a Pokemon Go player that no, that isn’t really a park or explaining what access tags are for.
Finding highway=path ways with missing tags is fairly easy, and it’s not that difficult to frame a question after a “hello and welcome” comment - “thanks for adding X - did you happen to notice if the surface was paved or not?”
Nothing new, right? And how has that worked out for paths, so far?
That was one of the show-stoppers for highway=scramble, the proposal. The decision, do I need hands (3,4 legs) or can I walk (2 legs) considered too much for the mapping community to decide. Curiously, the people voicing that concern all applauded sac_scale, where the distinction use of hands for convenience/balance or for advance is a decisive factor between grade T3 and T4. I suspect, because that would decide if some route is shown on OSM-Carto or not. In my eyes, highway=path is a vehicle to shove down something every consumers throat.
BTW: Have I said that – I enjoy scrambling. It is a very fun pastime. It even has some push in respective media here in central/western Europe. It is perceived here as stemming from the US (Sierra Club).
PS: Today I used both “destroyed:highway=path” and “highway=scramble” on the same feature; wondering how long that will last.
If we’re collecting uses of the word ‘scramble’, here’s one I found while fixing bogus path=* tags:
There’s even a video of the trail: https://www.youtube.com/watch?v=_BdCUoMYIQY&t=143s
I’m missing an option to move only some of the current usages to their own highway tags 
Watching the video, this does not show a scramble; Looks to me a typical sac_scale=demanding_mountain_hiking ramble.
Most eminently though I’d say, the video shows the absence of any path.
What I learned from RfC and comments during voting on highway=scramble proposal, it must be something that can be read from a tape measure and also be observable on aerials.
Youtube sent me here https://www.youtube.com/watch?v=nalkxF_jDe4 from the other video posted above. A very funny commenter! I’d say, this all within sac_scale=difficult_alpine_hiking – if done unroped.
PS: This for me would be outside of SAC scale, BMC scrambling grade III still https://www.youtube.com/watch?v=VpIqmSYepIY
That seems to be the main issue with scrambling being the main tag.
Having the scrambling scale as a secondary tag would be useful.
But scrambling overlaps the higher end of the SAC scale and the lower end of the UIAA scale. The guy in the second video states that some people use the rope on that grade III route, so that’s already a borderline case. The climbing route tag seems quite appropriate or at least overlapping.
What are the differences between a primary and a secondary tag?
If highway=path remains and a pathway=climbing is added, how is that different to other cases, where the path tag is replaced?
Other than the backward compatibility, which would be welcome to have.
No - the whole point is to not have things that aren’t really regular paths no longer showing on crap maps that just show highway=path and don’t care about other tags.
“backwards compatibility”, as you term it, would be a failure of the process here.
I just want to mention highway=via_ferrata. I am not aware of a single hiking map that doesn’t render it and general purpose maps don’t show it as generic paths. Nevertheless there are still people who think it should be tagged as highway=path
A see a path all the time sometimes narrow sometimes wide, not between the rocks but over the rocks.
backward compatibility and forward compatibility, at the same time.
That post has 11 likes, seems like a non starter to me.