There is no reason to believe that Vance would do better, The Republicans would have been better off 8 months ago Trump retired and endorsed Haley, who then chose Vance for Vice-President. Unlike the Democrats (whose split between WOKE and DINO is over ideology, e.g. WOKE supports Hamas and anti-Semitism in America, the DINOs don’t), the Republican split of MAGA vs RINO is based on style and campaign tactics more than ideology.
The “never Trumpers” are unlikely to rejoin the Republican party since they object to MAGA ideology and generally share the Democrat’s view that the Trump supporters are a “basket of deplorables”. TDS (Trump derangement syndrome) does make the Democrats act like idiots (e.g. calling for Trump’s imprisonment or execution, without or without a fair trial), and if Trump dropped out they might recover.