He is definitely swaybacked, but if he isn't in any pain from it, I see absolutely no reason why he can't go on and be a productive riding horse for 10+ more years (health providing). The most important thing you'll be able to do for him now is to make sure that your saddle fits him well. Swaybacked horses are notoriously hard to fit a saddle to so it may require calling out a professional saddle fitter. There are saddle pads made these days that can greatly improve saddle fit on horses like him.
He looks so much better since you got him, great job!!!