Will these dosages be forever or just until deficiencies are fixed and thyroid/coenzymes normalize? And then I'd drop back to lower dosages?

Yeah, so when it comes to the minerals, you want to take a higher dosage of them until your thyroid markers fall within the optimal range. You also want to wait until iodine, selenium and molybdenum are high enough within your hair.  

Once your thyroid and hair results are within the optimal range, you can drop back down to a lower dosage of each mineral. And by lower dosage, I mean you can take the daily recommended intake of each mineral.  

And when it comes to B2, you definitely want to continue supplementing with it every single day.