Well, it depends how expensive & how powerful Turion is going to be. If it offers performance comparable to an A64, I could see mobile A64's all but disappearing in favor of Turion. However, it turns out to be more of a 64-bit low-power Sempron, then I wouldn't count on a powerful GPU with it. The Radeon 200M chipset is supposed to be pretty decent, but just because they might use that chipset doesn't mean they will use a decent video card. Sony's FS550 uses the new Alviso 915GM chipset, but on most models puts an Intel GMA 900 in it :Q and DDR333 :Q
There is a thread here that links to another thread in another forum where Turion info is compiled, be sure to check there for updates.