"Once you hit level 50, you can choose to journey to another alliance's territory and experience a more difficult (and rewarding) version of those areas"

From what this says, it seems that enemy alliance areas will be treated as these "adventure zones" we've heard about( at least that's what I take away from it). The real question now is whether these will be instanced(most probable) or will we be able to encounter the opposing faction.

Source:http://massively.joystiq.com/2013/03/19/the-elder-scrolls-online-interview-paul-sage/

great saves me the hassle of multiple characters just to explore...although there is spying opprotunities in that.

Well, it was this or alt-making. Im kinda happy they did this. If faction pride is so important, why they even let us make character from another faction.

well if they are instanced then that should satisfy the biggest group of players. i mean it should make those happy that just want to explore(i hear this more than any thing else) and it should make the players happy that dont ever want to see the enemy faction players til RvR time. the only people i see not being happy about it are those that want to gank the lowbies

This.....looks......AWESOME!!!!!!!!

In that post it says; "he mentioned that once you hit level 50 and decide to play in another alliance's areas, you'll be able to play with friends in that faction. So at the endgame, things begin to open up and you can group up, chat, and run dungeons with players of other factions".
So, I'm guessing yes, you can play and do everything you could do with your own alliance in other faction areas.
How do I feel about that? It's okay, I guess, but I still wanted to fight, you know?
Perhaps if all the level 50's who can travel to other areas are the only ones who could fight outside of Cyrodiil? I think that'd be cool.
But still, this is good news!

wait we can group with other factions now? whats the point of factions then?