You're talking about roughly ~5T (the prior estimates I'm aware of) in costs for replacing the grid with a HVDC transmission line. That's a massive cost and undertaking. It's much more likely we see an incremental transition to point-to-point transmission in major industrial corridors (Los Angeles/Irvine to IE solar generation capacity in the future, Lousiana Basin, North Texas to the gulf, etc.) where major benefits can be cost effectively be realized.

A "full" transition is unlikely in our lifetimes due to the fact that the majority of the benefits can be reaped without needing such an expense.