I just happened to talk with Dave Metzner from Polar Lights while I was at Wonderfest back in June. Though there are no definite plans as to what'll be next, he said they DO plan to continue the line and try to keep things in 1/1000 scale, even though some ships won't make much of a kit (1/1000 scale Bird of Prey anyone?). In those cases the rule may have to be broken. We should start hearing about 2004 releases around October.
BTW, the NX-01 is going to be huge! Looks to be about 2 feet long if the prototype is the same size as the kit. DM said it's going to have about 200 parts! They really went to town on this one, so I can easily see them doing an Ent. E in 1/1000. It IS Trek afterall.