Thank you for the veryinteresting link.
In the comment section a bit-tech deputy editor appended "LGA1366 and X58 will still be around for quite a while, so it's still a good upgrade. P55/H55 on the other hand has a much shorter shelf life now."
On the other side, I could find at http://en.wikipedia.org/wiki/Intel_Sandy_Bridge_(microarchitecture) a list with anLGA 1356 socket instead of the LGA 1366, both with three DDR3 interfaces. (No comment about compatibility.)
Until Intel does notclarify whether their products will remain compatible I think I should better wait, or completely skip the Gulftown generation and remain happy with my current dual 604 system.