Or, even better, Shelly will support Matter and SmartThings Will be able to add matter compliant devices to a smartthings account, and everything will just work.
I say even better because the cost to the manufacturers will be lower since this isn’t a unique specific smartthings requirement, like edge drivers are. With matter, making it work for matter should make it work for a bunch of different platforms, with smartthings being one of them. So the company should be more motivated in creating it and keeping it up-to-date.
To be honest, I don’t see any device manufacturers except for a few of the smaller Z wave companies investing much time in creating edge Drivers right now. Most should go for Matter first and then see what happens on the smartthings side.
Zwave Device manufacturers are in a different position, since no one has yet announced a Z wave to matter bridge. So they have more reason to invest in a smartthings specific solution, especially if they don’t have their own hub.
But that’s just my guess, we will have to see what happens. 
More discussion of matter in the following thread: