I know that something was said about ZOS wanting to remove these entirely but they are most definitely still a thing. Not only are they ridiculous in their current application but with the way that guesting is about to change you're practically "bricking" characters and accounts. This needs to change. Maybe a 15-30 minute lockout when entering a campaign from another faction but you shouldn't be limited to restrictions on what you set your guest/home to.
Your game is not populated enough for you to have this kind of a lockout system with no travel to player options. Often, I find myself with no one on my guild lists or friend's list in Cyrodiil because it's that dead at times.
Here's an example:
There are 4 campaigns. Azura's, Thornblade, Chillrend and Haderus.
There are 3 alliances. EP,DC and AD.
You can set a guest campaign and a home campaign but never remove or desert from those campaigns ultimately locking your characters into empty campaigns.
Common logic can find the problem with the system above.
Assuming that all campaigns can hold a decent population (which they can't) you never set your guest campaign then you're fine however there is no way to remove yourself from a campaign entirely. Call it a deserter or whatever you want but this is definitely a problem. As a player that plays multiple factions for no other reason than to play multiple factions with other people this is a pretty big problem.
The PvP campaign restriction system is so intent on making things difficult for players that it's actually ended up bricking accounts for pvp. This should have been fixed or addressed when the first round of campaign reductions happened.
I know that you're aware of this problem but a campaign desertion penalty or option to remove a character from a campaign entirely needs to be implemented before the "Travel to Player" system is removed.