Will the surface of my teeth that were etched ever get their glossy shine back?

Etching removes minerals from the tooth surface to aid in bonding. It makes the tooth surface rough. This will not be fixed by rehydration. The tooth needs to be polished to a shine. 

Etching is applied to enamel to increase the bond strength of the bonding agent which holds the composite or tooth colored filling on the tooth.  Etching creates a dull and opaque surface appearance due to dehydration of the area which returns to a glossy appearance after the tooth rehydrates (couple hours to a day).  I have never used etch on a tooth prior to whitening as this could increase post op sensitivity and I don't see it providing an advantage.  I would return turn to your dentist to discuss this with him.