Since you asked... The Stinger is a great car developed by some of the best in the industry. But I feel like it was put together as either a signing bonus for Biermann, a swan song for Korean ICE industry, or both. Either way, it drove the reputation of Kia higher, gained Genesis a sporty platform, and shook some life into the typical sport sedan market lineup.
The Stinger, as we know it, will be discontinued. ICE engines are getting the backburner around the world in favor of EV development. Kia is no different.
Will it be a collectors car?
Maybe - time will tell. Fairly low sales numbers, a limited run, and good power for dollar are good signs. The community really seems to support these cars, so that's also a good note for longevity.
Again, maybe. Depreciation on Korean cars is still fairly steep, especially when looking at anything "luxury". If you're expecting to get top dollar, the car should either have low mileage or some other rarity (color, GTS, top-trim, etc). Otherwise, just drive it and don't worry about it. I don't plan to "save it for the next guy".
Repairs n parts will it be available?
Yes - for a while at least. Federal law says that manufacturers have to supply enough parts for the cars they produce to fulfill the warranty periods of those vehicles. So Kia having a 10 year warranty (in the US at least) will help keep parts in stock for a while. Also, this 3.3L (not to mention the 2.0L) engine appears in many other cars across the Kia/Hyundai/Genesis lines, so manufacturers will most likely keep making parts out of sheer volume and request.