I'll provide one perspective as an omnivorous coffee drinker. I drink everything from 7-11 machine coffee to the most pretentious pour-over outside the home. And everything from instant to my own pour-over (have gotten quite good at it) at home.

I am also a Starbucks Gold card holder and have been for years.

From where I stand, it looks like a packed market. Every major city has every angle covered in almost every neighborhood that can support it. It's a saturated space along almost every dimension.

Except for one: what I'd like to call "soccer coffee."

You see, in large parts of the world, the default coffee is neither the drip cup (America and Japan), nor espresso (Italy).

It is some downmarket variant of cafe con leche or flat white.

This is not like a latte or au lait the way Americans think of it or the Australian high-end flat-white. It is either an espresso shot or really strong (think Turkish strong) drip-ish coffee, with hot milk. The milk is either flat or has a weak microfoam. It is NOT super-foamy.

A cold variant is the SE Asian kind with sweetened condensed milk.

Here's why I call it "soccer coffee." In America, most coffee shops are built up around either a basic drip offering (ranging from Dunkin' to high-end pour over) or a basic espresso offering. This is the "anchor" drink, so to speak. Think of them as football or baseball.

In most of the rest of the world, whether upmarket or downmarket, the anchor drink is a cafe con leche type drink. Soccer. And not coincidentally, Latino countries do many great variants. In Colombia you have guys on the street walking around with a flask each of strong coffee and hot milk, and selling you tiny 2 oz cups that come in 3 choices: black, pintado (touch of milk), or con leche. In Puerto Rico you have really good cafe con leche in larger 6-8 oz cups at every street corner shop.

In India, you have "filter" coffee -- Turkish-strong slow drip with hot milk, poured back and forth a few times to create a microfoam.

And another important thing: in most countries, the milky hot coffee is pre-sweetened by default. Unsweetened, you have to ask for specially.

I think this represents a great positioning angle to attack. Why?

1. Growing Latino and general foreign population everywhere
2. Memphis = South = already has a tradition of sweet tea
3. There is already precedent that this works: ethnic restaurants do offer this type of drink, so Americans are used to it.
4. Gives you a signature cheap drink to bring 'em in: instead of drip or espresso, you can offer a self-serve pot of hot and awesome pre-sweetened cafe con leche for real cheap.
5. White and Black Americans will be attracted to a relatively new experience. You may attract a significant chunk of the currently non-coffee-drinking population that prefers sweetened drinks.
6. Starbucks is primarily drip-anchored, but does indifferent quality drip and espresso. Most competitors, whether they have chain, local-high-end or downmarket ambitions, tackle Starbucks head-on. So Dunkin' and McDonald's try to offer cheaper+better drip. Tully's, Peet's, CB&TL etc. try to compete directly. Local high-end try to either beat Starbucks on high-end espresso (signaled to the non-cognoscenti via latte art) or pour-over drip. But nobody tries to compete with them by simply using a different viable anchor drink.
7. It gives you are really easy minimum-viable-product: craft your killer con leche drink. Call it something like the "Memphis Shot" or something. Maybe use a gimmicky bean angle too. Start selling in small (4-8 oz max) cups at a farmer's market or a street corner. Scale up to a full location.
8. If you're ambitious, there's probably an unexplored angle to brand the thing more broadly with a Memphis angle ("Milky Blues"? "Big Easy Shot" "Muddy Waters Cup", "Fed Ex Shot" and potentially create something comparable to the Philly.
9. Most cafes that try to differentiate from Starbucks' dessert-like frappuccino direction by going purist and doing only the basics. This gives you a different way to create a lot of interesting variety without looking like a Starbucks me-too.

If not the OP, I hope somebody explores this vector of attack on the coffee market.