Thanks for the hint! We added that to our blog entry - please let us know if it sounds right to you.
Mozilla has stated plans to eventually turn it on by default[2] but I have yet to see any timeline or details of what the default config will actually be. Your article seems to assert that it will be on by default in FF62, where did Mozilla ever say this? Everything I have read seems to indicate that FF62 is just adding support, which is off by default, and requires a change to about:config to enable in the first place.
[1] https://gist.github.com/bagder/5e29101079e9ac78920ba2fc718ac...
[2] https://blog.nightly.mozilla.org/2018/06/01/improving-dns-pr...
While CloudFlare is being used for the opt-in study, you have no evidence that they will be used in any on-by-default scenario. Nor do you have any evidence that only a single DoH provider will be used globally.
Perhaps you should monitor Mozilla mailing lists.