Good points, but I did just want to comment on the above.
Smartthings has already announced that it is moving to a new app, new hub, and new cloud platform, and there will not necessarily be backwards compatibility.
Historically, smartthings has not worried about backwards compatibility. They’ve dropped more than a dozen devices from the official “works with SmartThings” list and they don’t seem to be coming back. (SmartenIT 
)The V2 had local video processing and the V3 hub does not. Multiple official features have changed multiple times and some functionality has been lost. (Remember the contact book?)
Even Samsung’s integrations aren’t safe.The gear watch integration broke and then appears to have been abandoned. The Artik cloud integration changed a couple of times, And I don’t even know what state it’s in now. The Samsung television integration broke for several months and was never repaired in the classic app, although it was fixed for the new app.
Just as one more example, with the old app you could set up an automation that would send a text, not just a push notification. With the new app you can only use push notification, which then breaks some of the third-party integrations.
So I just wouldn’t count on the idea that “as long as there is smartthings, Will continue to function.” That just isn’t the way smartthings has worked up until now.