While there's certainly a fair deal of hyperbole involved when Mike Zadorojny, lead content designer at ArenaNet, claims that the original Guild Wars "could last forever", what I'm taking from this brief Eurogamer piece is that the team is still committed to supporting it. Don't expect new content, though:
"The game itself was so efficient on the server side in terms of the resources, like, it runs on a fraction of the hardware that we need for running Guild Wars 2, so having that on the back-burner is nothing compared to GW2.
"We've been doing a lot of automation support so that the game itself could last forever, even without anybody really touching it," added Zadorojny.
"They're not necessarily making new content right now but there is a team that is monitoring if there are massive issues they're taken care of, and they're supporting them."