If you're buying a holster for your threaded-barrel G19, either order a threaded-barrel-specific G19 holster or...just choose a G17 holster. Options are good.
The OEM barrel is nice for most purposes - and it's probably unnecessary for anyone to replace it, unless they want to - but, when worn IWB in a G19 holster, a smoother, shorter barrel can be more comfortable. Barrel options are good too, and I wouldn't be so quick to sell your threaded barrel, because you never know what the future might hold.
I'm expecting suppressors to be legalized in my lifetime.