Let's put it this way....
Anyone worth signing to a big deal who is still young enough to grow with our core is not going to be realistically attainable. Why you may ask? They are either a restricted free agent (meaning that their existing team can keep this valuable player if they choose) and/or they will be heavily sought after by other teams (since young talent is very attractive to teams).
So what does that mean? That means you're probably looking at guys who are either role players or who will be too old to be a significant contributor by the time our core is ready to compete. Guys like Millsap would be a huge mistake right now. Millsap would not only take up a lot of our cap (cap space that can we use in trades to help us acquire more young assets), but he would also devalue our 1st round pick in 2018 (by bumping up our win total). And what for? By the time we'll be ready to actually get serious about competing, Millsap will be on the decline and we will have a #8 talent instead of a #3 talent from the 2018 draft. It's a short sighted move that hurts this team's future. Signing role players with our cap space isn't wise either. We're in the business of finding our stars. Filling out a roster with role players on 3-4 year deals not only takes away cap space and roster spots, but it also takes away playing time from our young kids who we should be developing (10 young players counting Bogdan).
The way you build as a successful team is to "stay bad" until you found 2 or 3 stars. If you start using all of your cap space when you have no established stars or even just 1 star, you become Portland (current). You become the Kings (with Cousins). You become the Pelicans (before Cousins). You become the Lakers (Mozgov & Deng) Why are we so hell bent on repeating the same mistakes?
Do not rush the rebuild! If that means maintaining a lot of our cap space and making our 2019 pick a valuable pick, so be it. The trade is over with. Don't try and hurt another team only to hurt yourself. It's in our best interest to be patient and smart with our cap. Ideally, we would resign Tolliver to a 2 year deal with the 2nd year being unguaranteed. That would put us at 13 roster spots taken. I'd look to make a trade or two bringing back 1 or two bad contracts with pick incentives. Ideally they would expire after this season, but I wouldn't take on any bad contract that doesn't expire in 2 years.
Preferably, the Kings should setup their contracts so that they have max flexibility in the 2019 offseason. Hield, Papagiannis, Richardson, Labissiere, Fox, Jackson, Giles, Mason, Bogdanovic, 2018 1st rounder, 2018 2nd rounder, 2019 2nd rounder, & any picks we received via the salary dump trades mentioned earlier. Cauley-Stein would be the only one we'd need to resign (if we end up wanting to do that). At this point, I'm not totally sold on him being our long term starting C. His shot blocking and rebounding are concerning, but we do have a while before having to make a decision on him. If we don't want to pay him the big bucks, we could potentially move him for future assets in the 2018 offseason or the 2018-19 trade deadline. If we did end up moving Cauley-Stein, you're looking at having approximately $62 mil in cap space with these assets under contract: Fox, Mason, Hield, Bogdanovic, Richardson, Jackson, Labissiere, Giles, Papagiannis, 2018 1st, 2018 2nd, 2019 1st (via salary dump trade), & 2019 2nd. That's 13 spots right there.
At that points, you can look to add a couple max players before you need to give all of your young guys a big raise. Guys like Booker, Brogdon, Stanley Johnson, Winslow, Oubre, D'Angelo Russell, Porzingis, Towns, & Myles Turner will all be RFA and guys like Wall, Irving, Kemba Walker, Bledsoe, Rubio, Harden, Kay Thompson, Middleton, Butler, Leonard, & Love will be UFA.
Hopefully Vlade has the vision and patience to not use his cap space in many of the illogical ways I have seen proposed here.