There is no technical barrier that prevents an oscilloscope manufacturer from adding a DRAM controller to their designs, either via an IC or as an IP core in their main FPGA.
The cost would be relatively low, too, and long traces are extremely useful especially for beginners.
Doesn't have an on-board DRAM controller, but I did look into the feasibility of it early on. In the end, I decided it was easier to just use the memory of the attached PC. Can record 10s of continuous data without dropping a single sample.
There is no technical barrier that prevents an oscilloscope manufacturer from adding a DRAM controller to their designs, either via an IC or as an IP core in their main FPGA.
The cost would be relatively low, too, and long traces are extremely useful especially for beginners.
Market forces will work to make this a reality.