Did he bang it or twist it, or is it an overuse issue? If it's overuse/age, he's on his way to Kemba Walker territory.
Even then I still think he’d be a top 10 player. He’s big without being out of shape. I think he could be effective into his early 40s, even with injuries.
I don’t understand what you mean by this. It’s obviously just speculation but if his knees became like Kemba it wouldn’t matter if he was 25 he just wouldn’t be able to stay on the floor (which is why Kemba went from all star to a guy making 4 million and out of his teams rotation).
Kemba sits in part because he’s ineffective, mostly because he can’t play Thibs’ defense. If he can’t score, he doesn’t contribute. That’s why he sat. (BTW, he’s been back in the rotation and starting for awhile now).
Lebron can post-up, rebound, pass. Size and elite passing ability matter. And, Lebron has a long way to go before his knees are like Kemba’s. Kemba had had “overuse” knee injuries for awhile now. Those knees have been detiorating since his surgery in Charlotte.