I would think not... I get SMS has been going down over the years, but for me, it's still the number one way I text with my friends. Same thing at my school: it's dominated by iPhones, so everyone is either communicating with iMessage or native SMS, there's virtually no middle ground (aside from the kids with iPod Touches who are forced to use messaging apps).
Besides, even if 99% of people on WP stopped using SMS, why dump it? It's already there, and if it could make even just a couple people happy, why bother trying to remove it?