Harada: It's not implemented in the game, but it could be possible with the PS3 and its firmware.
Will Jun Kazama make an appearance in any shape or form in Tekken 6, or any future game? - Deebo
Harada: Jun Kazama is currently missing (not to mention pretty advanced in years), but the possibility is always there.
Will there be a chance of there being guest characters from other fighting games like Street Fighter or Dead or Alive? - ColinMac93
Harada: It's always a bit difficult when you get different companies involved with each other; it's hard to push it through even if all the creators on both sides are for it. It's not that there's zero chance of it, though.
Speaking personally, I'd love to work on a title that takes all the fighting games and pits them against each other in some sort of ultimate final battle. I've spoken along those lines to the media a lot over the past 13 years -- "I'd like to make Virtua Fighter vs. Tekken," that sort of thing -- and nowadays I go out drinking with the VF team sometimes.
Tomonobu Itagaki, the Dead or Alive guy, went to the same university as me and we've drank together in the past, too. I actually have an invite from the Street Fighter IV guys coming up, come to think of it. Some sort of "dream match" game would be great to make someday.
Will we ever have a Tag mode again? - Melee_Sovereign
Harada: As mentioned earlier, we get a ton of requests for it. I'm going to have to think about it a bit.
Are there things you've discovered in making this game that you'd like to implement in TEKKEN 7? - Kain Carver
Harada: Oh, there are a lot of ideas...I can't say too much yet, though. For example, we've got a new idea for a facial-expression system for when people get punched and so forth. It'd be a real thrill to see in action, so I definitely want to do that.