Hoi,
For me it is not clear at all that how a long term road map will be of benefit. Quite to the contrary. I am afraid it will solidify what the WMF does and remove any benefits of the ability to adapt to changes due to new points of view. I do understand the need to plan, I understand that development does not happen in a vacuum and that it is important to be transparent about objectives.
The question is who such a road map has to be transparent for. Given that I am and have been active and care deeply for what we aim to achieve, I consider that I have a need to know because it helps me to plan what I work on. It helps me when I understand what future technology enables and it is why I have for instance worked on adding Wikidata items for Commons Creator templates.
My point is that exactly because of involvement, having some grasp where we are moving gives relevance to a continued expansion of the understanding how we are to achieve "the sharing of the sum of all knowledge".
When people with no involvement ask for a long term commitment with vague notions of "community involvement" I fail to understand how this will be of benefit. What it is that they aim to achieve and why is this involvement asked. My biggest worry is that it will ossify what we do and will make us even less agile and potentially less relevant. Never mind possible any good intentions we should not commit too far in the future.
Thanks,
GerardM