I wouldn't be surprised if they decided to field the DF-31A in the missile silos.
If China were to deploy DF-41s, theoretically that could be 3000 warheads which is excessive.
The US Minutemen missiles only have 1 warhead each, despite having the capacity to carry 3 warheads.
So the smaller (and cheaper) DF-31A could be used with just 1 warhead instead. That should give it the additional range to reach all of the USA. But some of the DF-31A could be fitted with more warheads at the expense of some range.