Email is routinely declared dead and routinely remains the highest-return channel most businesses have. SMS gets treated as a novelty and is often the highest-response one.
The reason both persist is structural rather than fashionable.
Every other channel is rented. Ad platforms change targeting rules and costs. Social platforms change what reaches your followers, and it is generally less each year. Search rankings move underneath you.
Your email list and your SMS list are yours. They move with you between platforms and nobody adjusts an algorithm that determines whether your audience hears from you.
That is the whole argument, and it does not go out of date.
Most businesses treat email as a separate programme from advertising. It is closer to the second half of it.
You paid for a click. The visitor was interested but not ready. Without a follow-up channel, that money is spent and the relationship ends there. With one, they enter a sequence and some fraction converts weeks later.
Very often the profitability of an entire ad account depends on whether that sequence exists. The channel comparison people run, ads against email, is measuring two halves of the same funnel as though they were competitors.
They are not interchangeable and the split is fairly clean.
SMS is for time-sensitive and short. Appointment reminders, confirmations, a message that fails if it is read tomorrow. Response rates are high partly because volume is low, which is exactly why it should stay low.
Email is for everything with substance. Education, nurture, anything that needs more than two sentences or benefits from being findable later.
The fastest way to destroy SMS as a channel is to use it for marketing that could have been an email. The permission is narrower and people revoke it quickly.
This is where most programmes get into trouble, and it is not a copywriting issue.
Email consent and SMS consent are different permissions, granted separately, and they need to be stored separately. One "subscribed" checkbox covering both is a compliance problem and, more immediately, a deliverability one.
Track what they consented to, when, and through which form. This is unglamorous and it is the part that keeps the channel working. Businesses that treat consent as a checkbox end up with lists they cannot safely send to, which is a slow and expensive thing to discover.
Post-enquiry follow-up. Someone asked and did not buy. Several messages over the following weeks, useful rather than pushy. This one usually pays for the whole programme.
Appointment reminders. If you book meetings or appointments, SMS reminders reduce no-shows. It is the least interesting thing on this list and often the highest return, because you already did all the work to get the booking.
Both are finite, both are automatable once, and both operate on people you have already paid to reach.