First, welcome to Long Range Hunting Forums
Next... I have a 300 WSM and I consider it to be about an 800-900 yd hunting cartridge at best, depending on load, elevation etc. I say this because the down range velocity (approx 1800 fps) required to open most bullets along with the momentum to ensure adequate penetration is reached at these ranges. Beyond that it is questionable as to whetehr or not your bullet will do the job. As for barrel life, the 300 WSM is a great choice. i dont have the refference and maybe someone else does, but a BR contest was won with a 300 WSM with 4000 plus rounds down the bore. I think the 300 WSM is a great cartridge and if you want to limit yourself to 800-900 yds on deer and elk type game, it's a good pick. However, to get to say 900 yds, you need a good rifle and and good loads. IMO most factory rifles and factory ammo will not get you there. Precision is critical. For a factory 300 WSM, I would recomment a Sub MOA VanGuard, they are very good rifles made by howa and have very good stocks. If you want to shoot at ranges beyong 500 yds, you should look at handloading if you are not already a handloader. It is critical to get consistant performance from shot to shot.
I think the best out of the box rifle and cartrdge(s) for 1K hunting would be the Remington Sendero in 300 RUM or 7mm RUM. These cartrideges will have a lot less barrrel life than the 300 WSM but they have better range and the Sendero has a great rep for accuracy. You can expect about 1000 shot barrel life. If you shoot 200-300 rounds initially for load development and practice then another 50 rounds a year, you have a 10+ year barrel, and when it burns out, you have a great platform for a rebarrel/build. If I where in the market for a Sendero (already have one) I would look for a good used one of the original SF's because I dont care for the new SFII wide beavertail stock and fat palm swell. The Sendero is a stout rifle wieghing 8 1/2 lbs.
As Boss Hoss mentioned, there is a lot to shooting 1K, but it's not undoable.