Originally posted by BigMackCam but it won't have fixed f/4 aperture (it'll be variable and slower). I don't believe those options are going to change any time soon...
I don't need f4, I'd be fine with f5.6 to even f6.3, because I already have the 70-200 f2.8, so the key value for another 70-200 lens is the size and weight, like it is with the 28-105. If I had the 28-105 and a longer also light weight, also f5.6, I could carry the kit everywhere. I've once seen and handled an F 70-210, and I was amazed at how small it was, so small that it can even fit in a large pocket of a jacket/coat.