So much for surprises. 
Yes, that is currently the plan.
A few comments on our thinking. First off, I've seen some people quoting a 2010 WoW Dev Twitter chat where we said "Limited Attempts didn't really work out" as one of the WotLK retrospective points. That was true as they were generally utilized in that expansion. In the very same dev chat, we also said "If we do limited attempts again it would probably be limited to optional bosses like Algalon."
Well, guess which boss Ra-den is probably most like?
The actual Algalon approach (or really, if you want to be accurate, the Vaelastrasz v1.0 approach) is not one we're likely to repeat. It definitely adds quite a bit of tension, but a narrow time window ends up being more about frantic racing back to the zone, rebuffing, and rushing to pull again, since it's hard to justify time spent strategizing while the clock is ticking. But even worse, a lengthy disconnect or some sort of server issue can completely ruin the entire week's effort. Having your main tank suffer a power outage 10 minutes into your hour on Algalon was not a happy time.
Now, as for actual limited attempts, aside from using them a bit too widely in Lich King (including on Normal modes in Icecrown Citadel), they also largely failed to accomplish their objective of focusing guilds on quality, rather than quantity, of learning attempts and progression. As many people recall, the cutting-edge guilds that were progressing in ToGC or Heroic ICC would commonly learn mechanics, practice execution, and refine strategies on their lesser-geared alts (and/or on Normal mode), before stepping up to risk precious Heroic attempts. That clearly wasn't the intended experience, and just added a layer of nuisance to the whole affair.
In our entire history of using limited attempts, there was only one boss where I'd say they actually worked out fairly well: Heroic Lich King. The main reason for this was that you couldn't access Heroic Lich King at all unless you defeated Putricide, Sindragosa, and Lana'thel on Heroic difficulty as well. And during the first few weeks of Heroic progression, that was beyond the means of essentially all the alt raids out there. After all, the point of running split main/alt raids is to funnel gear to the mains to maximize their effectiveness for Heroic progression, right? So by definition the alts are less geared than the mains, and if the mains can just barely, barely beat something, the alt group is going to be in for a rough time.
As a result, I don't believe we ever saw a single true alt Heroic Lich King progression raid. Similarly, I don't think we're going to see alt raids on Ra-den. The number 30 is also large enough that while one accidental pull or disconnect is of course still going to sting, it isn't crippling.
I'd also really like to emphasize that Ra-den is a true bonus boss. Lei Shen is the final boss of Throne of Thunder, just as Yogg-Saron was the final boss of Ulduar. Lei Shen offers an epic challenge, and should feel like the pinnacle of the zone as a whole. Ra-den is your reward if you manage to beat the zone on its hardest difficulty -- he's a bonus level. And sometimes the rules are a bit different on those.
Fuente: http://eu.battle.net/wow/en/forum/topic/6635413929#3
Pics related: http://imgur.com/a/KoUGb
RPV: al más puro estilo Algalon, en el 5.2 habrá un boss extra opcional, solo en modo heroico y con límite de tries (30). El boss final es Lei Shen, que es un boss de los de toda la vida. Ra-den es un "premio" si consigues derrotar la instancia en su máxima dificultad.
