Considering it use to be (and maybe still is) possible to get behind some gates and into other factions safe zones I'd imagine some people have them if they do unlock.
I believe @Hexys used to play with a group who knew how so might have more solid information. Apologies if I am wrong on that one and tagged incorrectly.
@Turelus - EU PC Megaserver "Don't count on others for help. In the end each of us is in this alone. The survivors are those who know how to look out for themselves."
^This
I know they will be useless even if you unlock them, but just for the sake of OCD, have anyone tried to unlock them?
like get a friend to chain pull you to the top base and run to wayshrine before you are killed etc
ZOS doesn't particularly care about completionism, seeing as I'm missing the Glenumbra Harborage (for some reason it was never marked as discovered on my map, even though I have my native alliance (EP, Stonefalls) as well as the Auridon Harborage)
Support apparently isn't able to discover map pins for you, despite the fact that it is entirely possible (they forcibly moved my character outside the Harborage, no reason they couldn't move me inside)
In short, no and ZOS really doesn't care about your desire to have all of the pins anyways
You can't. You are instantly killed if you somehow end up in the enemy's base.
Some time ago, I queued into Cyrodiil. And the game placed me inside the AD base instead of the DC base that I should be in. Not sure how that happened, but the end result was that the game instantly killed me as I spawned in.