For those interested, the link to the Pop Photo article:
The Future of Leica - - PopPhotoMay 2008
Summary of the key points:
1. No full frame on the horizon.
2. Improvements to high ISO quality will happen slowly. Use fast lenses. Hint at expansion of fast lenses in more focal lengths.
3. [As original poster states] Future upgrades pretty much stop with new shutter and LCD glass.
4. Wait for Photokina: More lenses plus more M announcements. More news in July.
5. Possible future DSLR in non-four thirds format.