> I presume when Vista users will get 64bit flash Linux will be able to see it too...
It'll probably take longer then you think.
Vista 64Bit is being sold in stores right now. If you have any computer or laptop that has 4 gigs of RAM then you'll get Vista 64bit whether you like it or not. And they won't tell you, because there is very very little reason to. (It'll be on the stickers, but they won't point it out as a feature unless they are trying to snowball you)
And guess what? Flash works flawlessly. My roomate bought a Compaq laptop a while ago and she could not tell you what 64bit was or is, but everything ran out of the box and everything continues to run. Zero issues installing or running any software for her.
It's still all 32bit, of course, but that _could_ be the same for Linux. The Linux kernel is perfectly happy running 32bit code on a 64bit kernel the entire AMD64 architecture is designed to facilitate the transparent mix and match of 32 and 64 bit binaries. One easy way to deal with Linux when running over 4GB of RAM is simply to take a 32bit system and install a 64bit kernel in it.
As it stands right now there is ZERO technical reason why you need a PURE 64bit system right now, or for the next few years. There is absolutely no point to it at all. Sure for some applications you want to have 64bit because they need excessive amounts of RAM, but otherwise you'll be almost always better off with a 32bit system.
Why? Because 64bit OSes consume significantly more memory and storage reasources then 32bit systems. This is why I won't run 64bit Debian on my Core2Duo machine.. there really isn't any point. (I only have 2GB)
Because of the unfortunate pure-64 goal of distributions like Debian it makes it artifically difficult to run 32bit software. Nothing in the kernel or architecture makes it difficult.. any sort of issues your going to run into is purely in userland.