I disagree. I believe they already have enough to charge her AND get a conviction. I think they're stalling for a few reasons. For starters, they're trying to give EquuSearch time to find Caylee's remains. While they can go forward without a body, it's absolutely in their best interest to do all they can to find the remains. It makes it easier on jurors to 100% conclude that she's no longer alive, but they're also wanting to give this child a proper burial. At least some DO want this for Caylee, even if the family doesn't.
They are also trying to stall charging Casey because once she's charged, that clock starts ticking and Baez could demand a speedy trial on Casey's behalf (which he would absolutely demand at this stage of the game). On down the road however, once the case is rock solid, he'll be the one doing all he can to stall.
By charging her with other things aside from murder, they were able to get her behind bars. With the bounty hunter and now the new bond companies in the picture, they're trying to get other charges that could put her back in. We could likely see more of the same really. LE can just start raising the counts on what she's already been charged with if they wanted. Since it's not likely these charges will come with any hefty bond attached, this trick may very well end at this point. It just depends if LE feels there is anything to be gained by doing so.
I don't for a minute, however, believe she will EVER face trial for anything she's charged with so far. It's nothing more than a smoke screen to enable LE to build the case stronger and stronger against Casey. We need to remember too, that much of the DNA evidence that has come back is only preliminary testing. If the sample sizes are large enough and not degraded too much, confirmatory tests will likely follow in short order.
At the end of the day, she will be charged with the murder of her daughter, IMO. I believe they'll likely charge murder 1, too. I guess that just depends on what those chloroform searches were. If they can show premeditation, I also believe they will seek the death penalty. Not so much because they'd want the sentence handed down, but rather, because they'd LOVE to have a death qualified jury.
From there, Casey can try to prove it was accidental, but everyone and their mother already knows that Casey cannot take that stand. By that point, it will be a done deal, IMO.