They can't really predict it. Just throwing numbers out there like a blind man throwing a dart.
The memory situation wont be solved until HBM memory is improved with something like 3D or vertical-channel-transistor DRAM so they get more capacity per wafer. Which some experts estimate that is still a decade out, hence the "10 years" comment from him.
They could have a break through tomorrow on something that could alleviate the shortage much sooner or never.
Similar thing happened with NAND flash memory and didn't get fixed (and cheaper RAM) until they went vertically 3D with it. Which meant more capacity per wafer for them. Basically, we need the same thing to happen to DRAM or possibly HBM4 will fix it sooner.
No one knows.
Heck, the AI bubble could crash next month and all those promised contracts could be cancelled which would free up the fabs to use those wafers for DRAM instead of HBM.