This is equivalent to something I called the "QWERTY paradox" more than a decade ago:
Back when the Smartphone market exploded, people disliked typing on a touchscreen and repeatedly stated that they want a device with a physical keyboard.
There was plenty of evidence, surveys, market studies, trend predictions, devices for these "Messaging-centric" use-cases were always part of this market-demand roster.
But whenever someone answered the call and built a Smartphone with QWERTY keyboard, the product failed commercially, simply because also to people claiming they want such a phone, at the point of sale they were less attractive than their slimmer, lighter, all-screen counterparts.
Every major vendor went through this cycle of learning that lesson, usually with an iteration like "it needs to be a premium high-spec device" --> (didn't sell) --> "ah, it should be mass-market" --> (also didn't sell).
You can find this journey for every vendor. Samsung, LG, HTC, Motorola, Sony.
The same lessons were already learnt for small-screen devices: There was a "Mini" series of Samsung Galaxy, LG G-series, HTC One, Sony Xperia. It didn't sell, the numbers showed that it didn't attract additional customers, at best it only fragmented the existing customer-base.
Source: I work in that industry for a long time now
As it stands the kind of people who want a smaller phone almost by definition need to be a bit savvier than the market in general to know such a thing still exists and along with that will have greater skepticism towards Android phones having any kind of post market support.
It'd basically have to come from Samsung to hit the all the price/quality/trust requirements. Feel like they've already got a lot of the pieces there with their corporate targeted XCover range just shrink them down a bit.