Will the formerly AGPL components continue to be dual-licensed under the AGPL as well?

If not, that's a problem, because the AGPL and GPL are incompatible, so that means that nobody can use the AGPL for new forks/patches on the product anymore.

(That's not quite true in that they can receive a copy of the product from someone who received it under the original AGPL license and therefore can and must redistribute it under the AGPL, but the point is that, when making licensing changes, you should always add a licensing option instead of changing it, because the latter isn't really possible, and the former is more explicit as to the outcome).