This is exactly what happened with the original analog and CDMA networks. Most carriers these days have converged on the HSPA and LTE standards which thankfully support SIM cards.
There's no technical reason why CDMA networks couldn't have supported SIM cards in their phones, but it was just never done. As evidenced by the overwhelming popularity of SIM cards, this particular battle has been won by almost unanimous decision in favour of the cards.
Only a few bastions of the original CDMA networks still don't natively support SIM cards (e.g. South Korea). But on the whole, it was already decided that SIM cards are here to stay since carriers demonstrated that without them, they are more prone to higher switching costs.
This is exactly what happened with the original analog and CDMA networks. Most carriers these days have converged on the HSPA and LTE standards which thankfully support SIM cards.
There's no technical reason why CDMA networks couldn't have supported SIM cards in their phones, but it was just never done. As evidenced by the overwhelming popularity of SIM cards, this particular battle has been won by almost unanimous decision in favour of the cards.
Only a few bastions of the original CDMA networks still don't natively support SIM cards (e.g. South Korea). But on the whole, it was already decided that SIM cards are here to stay since carriers demonstrated that without them, they are more prone to higher switching costs.