@jzen121 no it won't, we'll keep it up as long as players play it! ^SL
Yet more misinformation from a certain someone. No big surprise.
There is very little cost to Arenanet to maintain GW1. It's possible they may stop updating it at some point after GW2 launches, but as long as people keep playing Guild Wars 1, they will keep the game open. The Hall of Monuments tie in to GW2 will continue to be available for progression in GW1 after GW2 launches, so some completionists who play GW2 may want to play through GW1 for the exclusive cosmetic items.
A lot of people continue to play GW1 and although I expect that a fair portion will leave for GW2, Guild Wars 1 will likely continue for some time.