There are other models, like sell the razor cheap and charge more for the blades, which can support a product ecosystem, albeit a smaller one than that for grooming products.
Consider that the FOB price for replacement cellphone cameras is under $5 in quantities of $100. The hardware is cheap, the labor of installing it into a phone that needs repair is not. But if you make it user-installable (as here), you can sell the exact same camera for maybe $20-30, with only a minimal increase in the cost of production for the modular package. So this could work out quite nicely for component manufacturers by giving them a small additional revenue stream from enthusiast/hobby buyers.
All those people complaining that it won't be competitive with other phones for consumer dollars are totally missing the point. Of course consumers will continue to prefer all-in-one products from brand name manufacturers like Apple and Samsung, for the same reason that most consumers want a car that Just Works rather one that requires them to be an amateur mechanic.
And yet, there's a thriving retail business in auto parts, because a lot of people do like to hack on their cars or carry out their own repairs. And likewise, there's a market for modular phones among hackers, engineers, high school and college students, and all sorts of other niches, who want flexibility but don't necessarily want to go down the Arduino route with soldering and building their own cases and PCBs. Simple example: stick two camera modules into one of these things, and you have a super cheap 3d camera platform.
This will be absolutely huge in the developing world where utility >> convenience or aesthetics.