Is there any real reason why we need a full tear-down of the DS1**4z series? I very much doubt that there will be any fundamental difference between it and the DS2**2 series. The power supply will be the same. The controls will be fundamentally the same. I very much suspect that the inputs will just be a second copy of the input for the 2-channel scope, Fed into the same DSP chip.
The only thing that might be interesting is the logic analyser. Even then, I would suspect that it would be a single chip solution, so not really much new content there.
just my $0.02