My predition:
Goldwater votes for it. As far as I've seen in writing and interviews, he said nothing against it (unlike others like John Tower) and he did vote for all the other civil rights bills previously, and his justification for voting no in 1964 did not apply to the VRA.
As far as the idea he would do it for political reasons, I don't think a guy who went to Tennessee and bashed the TVA or spoke against Medicare in front of a group of seniors was gonna be that ruthless.
He said so himself in post-campaign interviews that he knew he would lose and he sure ran like it.
With Goldwater not being associated with being anti-civil rights, Wallace likely runs.
A NSS-type scenario is possible.
Personally I believe that a Wallace vs Goldwater debate is likely, as both candidates will want free airtime and the possibility to prop themselves with a national audience. , with Goldwater most likely winning in the eyes of northern voters (if only by getting the visual that he's not George Wallace) and losing in the south (as Wallace runs as a New Dealer type, but still anti LBJ, appealing to the economic views of the majority of southerners at the time)
Goldwater might win Idaho, Nebraska, Kansas, and Utah, the closest 4 states OTL, but lose every state he won OTL. Heck depending on how the debate and follow-up goes, he might do better, especially if LBJ primarily sics the CIA on Wallace not Goldwater.
The reason being is that Goldwater might be seen as the only thing standing between Wallace and the Dixiecrats being taken seriously as the main opposition party to the Democrats. He also has the positive of not being literal hellspawn in the eyes of voters, what with George Frickin Wallace running right after standing in front of the schoolhouse door.
In addition, Goldwater now has two foils to run against-LBJ and Wallace. With both taking different polls of the civil rights issue, Goldwater seems like a moderate, which greatly helps his image overall.
Heck, he can have a chance to cry out against the eastern establishment media he so hated as liars who would put him with this "Insert Goldwaterism to describe George Wallace Here".
In addition, LBJ would focus more on destroying Wallace than Goldwater and instead of following Goldwater around, follow Wallace. After all, at this time LBJ's economic initiatives seemed less likely to be defeated (thus ruining his legacy) than his civil rights initiatives.
Heck, in this scenario LBJ has a chance to beat FDR and go 50 state sweep if he gets enough blacks voting in the south and Wallace and Goldwater to split votes just the right way, especially if they never debate each other.
If you want a real dystopia/crisis scenario/adventure, have LBJ's spying of both campaigns leak before election day...
Would make for a fun timeline either way...