When I was commuting daily in the rain, I'd wear out on average one rim per year. The drill then was to grab (another) Mavic Open Pro rim from the rack, and move the spokes one by one from the old rim to the new. Took about an hour per wheel, including truing. While I was doing this I could watch TV. Good for another year. Since spokes last 100,000's or more stress cycles, these should last longer than me. Spokes on the front wheel should last forever, if you are running rim brakes. Spokes will last longer on rim brake bikes than disc-equipped bikes, due to the transmission path of braking forces.
Most folks kill rims from impacts long before they wear out, so the issue of rim wear is largely moot. At the high-volume bike Co-op I work at, the ratio of wheels busted from impacts vs. rim wear is 10:1.
Economics: rim brake pads cost what? $5 per pair on Fleabay? And Open Pro rims are now selling at less than $25 each. And new disc-equipped bikes are substantially more expensive than the previous generation of rim brake bikes, so someone buying discs for costs savings will never catch up.