Will a Shimano Deore 10 speed kitted bike become obsolete?

That probably depends on what concerns you're likely to have? Personally, I wouldn't worry too much about the drivetrain. If the frame is good quality, cost effective, and meets your needs, that checks a lot of boxes. Long term maintenance of anything is always a question, but bike drivetrains seem to have a good history in this regard. I tend to keep bikes and repair/upgrade them rather than buying new every few years, and haven't had any major issues maintaining bikes for at least 20 years.

In general, I've found that fixing, replacing and upgrading shifters and derailleurs over many years isn't a major concern. Bottom bracket standards seem a bit all over the place, so that might be a place to check the specs and parts availability on.

Things I'd keep an eye out for, especially with carbon frames, are proprietary shapes on what should be almost universal components. Items such as a non-round seat tube, headset mount or handlebar mount. These seem like larger maintenance considerations to me than drivetrain elements over the long term.

Overall, I haven't found parts availability to present an issue. Used parts for various older drivetrains are pretty widely available online, and bike shops that have good selections of used and new old stock parts don't seem hard to find. If new parts for older bikes are preferred, there are also smaller brands like microshift that fill that niche when the majors move on. Also, thumb shifters can provide a universal option if maximum longevity is the goal.

At some point, it may make more sense to keep the frame and upgrade the drivetrain. For example, I recently upgraded a 15 year old hardtail that had an XT 3x9 drivetrain to 3x11. The rear hub was an XD already, so the new cassette wasn't an issue. The rear derailleur mount standard hasn't changed, so that wasn't an issue. I kept the 3x crankset and the original front derailleur because chainring spacing changed, and I didn't have the tools to deal with swapping the crankset and bottom bracket. In this case, most of the swing difference was accounted for in the new derailleur rather than the shifter, so it all worked out. However, a crankset change remains an option if the FD needs replacing in the future.

Hope this helps, it does sound like a really good deal.

Great Stuff, thanks!

Exactly what @pmscientist said. 
Typically, you can buy drivetrain stuff for a long time still. Perhaps not the top of the line models, but why would you put top of the line components on an old bike?

Also remember, that the crank and brakes are not “speed specific”.
So you can always replace a few more parts in the future and end up higher end. 12 speed chain, shifter, Cassette and derailleur, under $300 .

I still use 9-sp. Plenty of drivetrain components available. Just bought several new XT cassettes, and had the choice of 8-10 other models and brands

Good stuff guys, thanks.