The US has too much going for it in terms of population size, geography, natural resources to fade to the extent the UK has. At least in the near future.
There are about 5 states that are red enough to even conceivably split off. But those states also have such low populations that they have disproportionate power that they would lose in a split. And none of them have any kind of state identity that would make up for that.
The only states with enough state identity to even consider splitting off, Texas, isn’t red enough to do it.
Very blue states aren’t all that blue (the presidential vote margins in 2024 were much smaller than they were for the reddest state) and they are far too integrated with nearby red states.