OKC is in a bit of a situation financially.
Now how much will Ibaka get in free agency? I would look at how much DeAndre Jordan got, about 10 million for the first year, minimum. I would actually prefer Ibaka. So add 10-12 million to 2014 and 2015.
Maynor they may drop.
Now Harden. If you have Durant, Westbrook and Ibaka for 43 million, can you even afford Harden? He must be worth at least what Manu Ginobili makes (not to mention how young he is) so about 12-14 a year. That would put the team at 57 million on those 4 players plus 15 million on guys already signed. I guess it's doable, but it would be expensive. That is also assuming Harden and Ibaka sign for that little. I can see both being offered more (esp. Harden).
Let's say they do trade for the #2 pick and pick up Beal. They now have Beal for 2-4 years (two team options). They get him at about 3.8, 4.6, 5.5 and 6.9. That is a savings of 2 million the first year and probably close to 7 million the next three years. This makes signing Ibaka relatively easy, and gives room for a more veteran presence. It's a shame, but it's not a bad move if they go after Beal.
I don't think Drummond makes sense, with them likely keeping Ibaka and Perkins there for a few years. They will have way too much invested in those two guys it have Drummond on the team. If Perkins were only there for 3-4 million or 1 year, Drummond would make sense.
In fact, Beal is really the only player that makes sense, unless you believe in the Lilliard hype (and even then #2 is a huge stretch).
EDIT
From the Charlotte side of things, this doesn't make much sense. You likely have Kemba at PG and Henderson at SG. They need players at the 3 and 4 position more than the 2 and there are good candidates in the draft. However, if they were to make separate trades then this might make sense. I could see Henderson being worth a mid-first.
I'm no expert on the salary cap, but I think it would be a shame if OKC was forced to break up the Durant, Westbrook, Harden, and Ibaka core. At some point, you have to reward a small market team for playing their cards perfectly in the draft, staying patient with their youung players, and not making any desperation free agent signings that would render them unable to hang onto these young pieces. I read that there may be a rule in place that allows teams to exceed the salary cap to re-sign players that they drafted, but I'm not positive.
Either way, if OKC is indeed forced to part way with one of their core four, wouldn't you try to trade Ibaka to a team in the top ten and then try to draft an Andre Drummond type player with that pick? You'd think at age 22, Ibaka, who averaged 12 points, 10 boards, and five blocks in just his third year in the league, would be worth more to a team trying to rebuild than would a guy like Perry Jones, but I'm not sure. Say you trade Ibaka to a team like Portland or Detroit, grab a pick in the top ten, and select Perry Jones or Andre Drummond to pair with Perkins on the frontline. Doesn't that make more sense than shipping away James Harden, one of the best 15 offensive players in the league?
I don't necessarily agree with your take on Charlotte. If I'm the Bobcats, everybody on the team is expendable if it means you can bring in some real all-star talent, somebody who might generate some buzz around town. Gerald Henderson is a role player at best, IMO, somebody who doesn't defend, doesn't pass, can't rebound, and could barely crack the 16 PPG mark on one of the worst teams in offensive memory. I don't know how much you trust PER, but Henderson was a 14.0 last year while Harden was a 21.1. If you really want to keep Henderson, just move him to small forward or play a three guard lineup. This is a desperate franchise, and if you can bring in a 23 year old, all-star type player, you'd be foolish not to do it because of Gerald Henderson IMO. As many scouts and GM's would tell you, when you're as bad as the Bobcats (and God, they're bad) you don't make moves based on need. Even if you have to move Kemba to get some proven talent in there, you do it.