That will only happen if they become confident that he will lose re-election. At that point, there will be a whole lot of born again Never Trumpers.
However, I do think that some people who were on the fence already have hardened their hearts against him, and some who were silently against him might grow publicly against him, but note that the people speaking out against him are mostly retired from political careers. I'll bet you won't see any condemnation of Trump from any Republican politician whose still faces a primary election.
I do think his reaction, not the killing itself, has hurt him politically., but will it be enough? His base will lap it up, but his base isn't big enough for him to win re-election.