Would it be possible for a new technology to make RAM obsolete?
There is nothing special about RAM. Before electronic computers were invented, mechanical data sorters and tabulators used punched cards as their main (and only) memory. Early electronic computers used many different technologies for their main memory, including vacuum tubes, acoustic delay lines filled with mercury, the screen of a cathode ray tube and tiny rings of magnetic material looped around wires. If a memory technology was developed that was just as reliable as solid-state RAM and at the same time significantly faster and/or cheaper then it could certainly replace RAM and make it obsolete.