I think it’s quite obvious what this is going to be: an SDS2kX combined with the new system architecture and additional user interface elements of the SDS1204X-E plus some further improvements like the 10.1” capacitive touch screen, enhanced probe interface, reference clock in/out and external monitor support.
Compared to a SDS1204X-E the SDS5kX has 5 times the sample rate, thus enabling 5 times the bandwidth for the top model and it has almost 18 times the sample memory, hence can capture up to 50ms at max. sample rate.
I guess this is going to be a pretty interesting product once again.