P: Ability to sync Lightroom Classic keywords with the Lightroom Ecosystem

@PatRick, the perpetusl version is discontinued..It also doesn‘t have synch with the cloud version so is no part whatsoever of the problem discussed here!

It is still possible to buy Lightroom 6 perpetual licence here in the UK but I have heard rumours that may well be the last version. Sylvain, have you seen an official Adobe announcement that the non-CC version of Lightroom will be discontinued or are you just assuming that will happen?

Johan Elzenga. You will not be able to buy Lightroom classic anymore. You need a plan to have it, a plan that include the cloud capabilities . A bit of consistency would be greats

If Adobe develops something new it should make sense to its users, right? That is my expectation and it is not being fulfilled at all. What sense does it make to have two independet solutions, if one could support the other? Everybody is talking about workflow and what does Adobe deliver? Workflowinteruptions! 
Sorry for being a bit emotional here, but it is true not "only" in this instance but also cannot sync libraries from LR CC cloudversion with Adobe Portfolio both ways, neither export file names into Adobe PF. So each single one a beautifully made app but they do not function together. 

What they say is that Lightroom Classic is the desktop oriented app and Lightroom CC is the cloud oriented app. They could have (and maybe they should have) removed all sync features from Lightroom Classic, to make it perfectly clear where this app stands. I’m glad that they didn’t do that, but the result is that people keep having expectations for new or improved sync features that will not arrive.

What I do not get is the attitude of Adobe, there is industrial secrets involved here. They can say something like “we want to bring all the (keys) possibilities of LR classic to CC little by little to this modern platform so nobody will need classic anymore. Therefore our focus is on making this a reality as soon as possible. The sync between classic and CC is more based on best effort.”
It would be clear for everybody.
The subscribion sheme imply a trusted partnership between us, clients and adobe.

I'm not so sure if this is true because they are continuously adding new features to Classic. 

Exactly !

And even: at first, they said it was a technical reason. No one believed it and now it is "by design" and "Classic will not get any new sync feature" and "switch to LR CC if you want more sync capabilities".

Your statement

what they mean is "we don't want to spend any significant money on improving Classic as it will divert resources from CC development and we are trying to get people off of Classic and on to CC so why would be do something that would encourage people to stay on Classic?

is exacly right. I would also add: "Adobe wants the users to switch to cloud also because it's more difficult to migrat to another solution afterwards!"