Again, which part? Half of it has already happened. Biden has just pulled out giving US voters an alternative to Trump that isn't seen as being far too old and incapable- as Biden was bring portrayed. Let's see how that starts to affect polling over coming months.
"Live updates: Joe Biden pulls out of US presidential race, endorses VP Kamala Harris for president; Democrats praise decision; Republicans call for him to resign immediately"
https://www.9news.com.au/national/joe-biden-us-election-2024-live-president-pulls-out-of-election-race/1206dbd3-e46a-4c7f-a65c-cef6e2601099
