That's quite the understatement.  The new forum software was being talked about when I joined the forum over 6 years ago, as OP pointed out, and I'm confident that if Theymos really wanted to upgrade bitcointalk he could easily do so in a much shorter time period.  He's got access to the necessary funds and I'm pretty sure he'd have all the coders he'd need, because if that were the bottleneck there would be tons of members stepping up to help.

So I've no clue what the deal is with this mythical epochtalk version of the forum, nor do I care personally.  I happen to like this version just the way it is, without many changes to the look and feel and function of it.  However, I do find it very odd that this thing has been strung along for so many years without an explanation as to why that's the case (or at least I've never heard one, but I'll confess that I have the New Forum Software subsection on ignore, so I could be missing one if it exists).