Must be in Stormwind or Orgrimmar to opt in or out of world PvP?

[Neversage]

I think it's great. Makes you commit so you can't coward out of it. too fast, but you can turn it off for RP or raid night.

[Sentynel]

This has to be a joke. Please tell me it's only temporarily for the alpha, because it's fucking stupid.

This is a thing since Blizzcon. Welcome to the internet.

[Ithekro]

Could someone with Alpha access or who has seen this situation in aan Alpha-Stream please answer this question:

How does the new system handle situations that flag you automatically by aggroing NPCs or entering faction-zones?

In more detail: If my PvP-Flag is set to "off" and i fly into an enemy city...what happens? Is it switched on? Do i get transferred to a PvP shard of this city?

Likewise, if i attack Questgiver-NPCs of the other faction while my PvP-flag is set to "off"...let's say on Hellfire Peninsula (no idea why i came up with this location!)...what exactly happens? Am i not able to attack them? Does nothing change at all, because the whole system only applies to the new continents?

I would really like to know, because whatever i imagine to happen..it always ends up strange.

Let's assume i simply cannot attack faction NPCs if i am not flagged....then i would still be able to aggro and train them with a tank+healer...imagine how somebody pulls all the important NPCs of your quest location and you cannot interact with them. You cannot fight them off either, because no flag.
Let's assume i still CAN attack them but get flagged instantly. This would contradict the "only switch in capital"-rule...it would also cause the question of what happens when i get flagged this way. Do i get transferred away to a PvP Shard? That would still leave the NPC in my old PvE-Shard dead, since i would be able to oneshot it and nobody could do anything about it. Do i not get phased? Then i'm sitting PvP-flagged on a PvE-shard where nobody is able to attack me.
Are the NPCs simply ignoring me completely? That would be fucking stupid, because then i could walk through the streets of Stormwind as an Undead, flirting with the City Guard?

What i ASSUME to happen is i get flagged the instant i enter the zone/aggro the NPC and get phased away. Which would still be shit, since there are MANY questlocations throughout the world where you can very easily aggro enemy NPCs just riding by...always getting PvP-sharded whenever that happens and having to return to some safe-zone to switch it back off seems inconvinient...but still the least strange solution, i guess.

So...if anybody knows how 8.0 handles this...please answer.

I can see an alternative based on what they did with the Class Order Halls in Legion. If you aren't part of that class, you get teleported away. So it might become a thing that if you are say Alliance and wonder into Tarren Mill while flagged for PVE, you get teleported away, just like if you try to go into the Horde side of Dalaran. That way you can't get flagged and the NPCs won't aggro on you cause you'll be gone first.

[Airwaves]

You will receive more XP, rep, loot etc when on a pvp shard. People will more then be happy to return to a capital. Not that I think it matters. People will stick to pvp or pve and never switch.

This stops people going to a pvp realm then just changing at will when it gets to hard. If you are going to get the bonuses you should be locked to the shard outside of cities.

[Ophenia]

Likewise, if i attack Questgiver-NPCs of the other faction while my PvP-flag is set to "off"...let's say on Hellfire Peninsula (no idea why i came up with this location!)...what exactly happens? Am i not able to attack them? Does nothing change at all, because the whole system only applies to the new continents?

This situation already happens on PvE realm, you are not able to attack PvP targets until you're set for PvP.
But, if this PvP-on NPC attacks you, your PvP flag is automatically activated.

For example on PvP WQ on my realm, I cannot attack enemies without setting manually my flag on, or I have to run through mobs for them to attack me before I can reply.

I guess this will be handled the same in BfA. That may be the only situation where your flag automatically activates, or they will implement the Order Hall way, with someone stunning you and teleporting you outside of the area if you're not PvP-flagged (but that would be weird).