The way these announcements generally work in my experience is that we will know a few days before. That's all.
As far as a 18-200 goes I figure Canon reckons they can do better. And they can.
The 5D3 before the 1DS4 seems to me and is a consistent rumor now. I expect This strategy works so long as the 1DS4 is something new. I'd guess it has a new name too.
There doesn't need to be 3 pro bodies.
Justin's Canon Roadmap
5D3 - 32 mp, 5fps, improved high iso and dynamic range, vastly improved AF mechanism, funky weather sealed
24-70 f/2.8 IS - it's really ridiculous not to give this lens an IS motor
1D5 - 18 mp, full frame sensor, 10 fps, full body, high iso lord of darkness
7D2 - 24 mp, APS-C, 10 fps, small body, lives on the sidelines and Wildlife shooter superteles
Canon 645D - 50 mp, 3 fps, 12 stops dynamic range, new mount, advanced auto focus,
24-120 f/4 IS
efs 18-200 f/3.5-5.6 IS
15-60 f/2.8 IS