My thought would be that initially it would lower value. At some latter time; and people with experience of discontinued calibers can chime in, the rifle/caliber combination would be worth the same as any other used T3. Perhaps it would sell faster when offered for sale, but unlikely at a significant premium dollar. If the gun was a top end gun with high grade walnut and engraving it would hold value, but hey the T3 is a $800 gun so if it loses value one is still not out your kids inheritance.
enjoy the reloader only rifle, and maybe you find another 308 family T3 barrel on the EE, cheap, for when its time to rebarrel.