Those wheels are very good for touring. When you wear out those rims you'll be looking for new wheels down the road,just as you would for any new extra heavy duty wheels you bought now. The only circumstances I could see you needing to replace the existing wheels is if you are over 275lbs carrying over 35lbs on the rear wheel alone, were going to be FAR from civilization and you simply wanted as much metal as you could get on the rim for long life as the brake pads wear it away.

Extra heavy duty wheels won't prevent catastrophic failures, they'll just last longer. I've had front end crashes that ruined the frame but not the wheel, crashes that ruined the rear wheel but not the frame.

With same rim and number of spokes the you might get the front wheel to last two or three times longer than a rear wheel so if there's any question of needing something tougher you could get a heavier duty rear wheel. If this is your first venture touring and most of it is in the US I'd just ride the existing wheels to the ground.

How heavy are you?