10 Nov 2008 at 11:56 - 66
I guess the question is not clear: many players aren't "going away" because they're simply playing the game from time to time, irregularly and when they have the time. A game like GW can't be dead, because by the very nature of free2play, you can happen to not play for 1 month, but play a lot the next, or not play for 6 months and then come back. Of course, at a given point in time, you can compare estimates of the number of people playing at this time, and it seems obvious that this number is decreasing (a good example of that being the number of districts in LA and Kamadan during MKT's hat event). But contrarily to pay2play games, you're not a "subscriber", your GW account is permanent and you don't feel obliged to come each month because you're paying for that.
So we can find valid arguments to answer yes and no to the OP, the same way there are valid arguments to "prove" and "disprove" (double-quote because it's a matter of opinion, unless you're Anet and know the numbers) that GW1 is dead. I think people are in fact talking about their personal experience of GW1 now compared to months/years ago, you see less people on the guild roster, in AC, in the towns/cities where you play/chat, or less GvG games. It's also the nature of MMOs to look for people, they're supposed to be online, meaning you're supposed to meet and play with people (apart from the technical aspect that the architecture is client-server, I'm talking about the gameplay), and GW1 feels a lot less MMO than the other MMOs out there (it's also because at one point Anet decided to make the game single-playable).
But, and it's a big (huge IMHO) "but", it's free2play, you can always put it aside for a while and come back (look at The Return in PvP, I can imagine how difficult it's for them to come back from the very top after years of inactivity, yet these guys are here for the fun and I guess they got some). Anet may well have our money, but they're not asking for more.