Dallas is going to have to sign a big name free agent because if they don't I just don't see how they can assemble much more young talent around Luka. Most likely they won't have their pick next year. Luka is going to keep them good enough to avoid picking Top-5 next year (to keep their pick). He'll also keep them good enough to stay out of the top-5 the following year as well.
So you run into this problem where you have a phenomenal 19 year old that makes everybody better......but you don't have much young talent around him to make better.
Harrison Barnes sucks. He just flat out sucks at everything in basketball other than scoring. No passing, no rebounding, below average handle, no intangibles, no leadership. Total waste of a big contract and a big disappointment from his draft hype. Wes Matthews is just a bit more skilled than Barnes but the results aren't there and clearly the Achilles injury took a lot out of him. DeAndre Jordan is still a solid big man but he's getting older and he no longer impacts the game defensively like he used to. Jordan may not be on the Mavericks next year anyways. That leaves Dennis Smith Jr. as the only guy in the Mavs starting lineup with room for growth. Problem is he's a low IQ player and hasn't shown much ability to adapt.
The Kings depth level of young talent is vastly superior to the Mavericks.
Mavericks are going to have to attract a big name free agent and also hit it big on a late first round or second round pick.