In my opinion a decision is to be made by scirra: support it or deprecating it, so we would know at least what waters we are into.
the idea of kongregate making a plugin is not that bad honestly, but it is quite unrealistic unless we truly give them a valid reason, and even then it represents more work for them, but it would be the ideal solution.
scirra maintaining the plugin will mean it will work for a time then break again, it should be that way since they advertise it as a platform on the front page ("Easily reach the web by publishing to your own website, Chrome Web Store, Facebook, Kongregate, NewGrounds, Firefox Marketplace or use our Scirra Arcade to share your creations.") so they must guarantee it, it would be the normalsolution if the ideal one doesn't happen
the third solution is a plugin opened like the one cocoonJS got, could work, could not work.
then the solution of waiting for someone to do its own personnal plugin, not a great idea long term IMO
(there is also the solution of implementing the API without a plugin but unsure how doable it would be, and it would imply coding so a big no for most people).
so for me as long as it is not deprecated, it is supported and so must be up to date, that is my reasoning, and is what the front page implies.