Until very recently, most/all of their phones had alternative Samsung-produced chipsets available in various markets (Exynos).
They've got their own app store as a built-in.
And they also maintain their own small-system operating system, with Tizen, in case it all goes to shit.
They've been working very hard on parallel development for quite a long time. They're probably better-prepared to jump ship than any other top-tier manufacturer of Android cell phones is.
Motorola Mobility? That was spun out of the stodgy-big batwing mothership in Chicago a long time ago -- and first purchased by Google, before being sold to Lenovo. Subsequent to Google's influence, whatever remains is ill-prepared to jump ship, but that was certainly a design intent. That behemoth is much more dug-in.
So the outlook is certainly gloomy, but it's not all darkness.
(In terms of things like banks only supporting one OS or another: Gosh. Prior to the entrenchment of the smart phone age, I never installed a company-specific consumer banking application on any computing devices at all. It was OK. I just used Sir Tim Berners-Lee's World Wide Web to do that stuff, sometimes with a side dose of SMS on my dumb-phone for active notifications.
And still today, I don't have banking apps for most of the companies that I do banking-stuff with -- and I get along fine with keeping track of the money I have, the money I owe, and the bills I need to pay.
Maybe the right answer here is to shore up the utility of the platform-independent WWW.)