Within the part of the country where they’re at least a non-trivial minority they’ll certainly be able to frame at least part of the agenda for state level legislation and for local-level enforcement. That is very powerful. All the more so if they can keep it up for 2, 4, or 10 years.
As well, IMO the US contains a lot of people who are closet fellow travelers. In the privacy of their own mind they’re thinking along the lines of “Those ultra-racists are crudely overdoing it, but thank goodness somebody is finally standing up for us fundies / whiteys.”
To the degree the fellow travelers can be coaxed into making even vaguely approving noises in public, suddenly the tide of white supremacy could blossom from WAG 2% rabid adherents to – big WAG – 30% rabid + semi-adherents.
There are lots of ways the “unthinkable” is actually the “unsayable-in-public”. Once those things do become sayable in public the zeitgeist can shift a very long way in a very short time.
IMO the big news with this will be the vastly lopsided geographical distribution. This will throw into very stark focus the reality that we have 2 USAs with very different ideas of how to run the country: the non-deep South urban/suburban, and the rural and/or Deep South.
The fact the former demographic is a hefty majority of the people but the latter is a hefty majority of the land area and statehouses and federal legislators will lead to lots of controversy about voting arrangements, just as it did in 2016.