The seal won't disappear...I mean it will if she uses all of that chakra but it doesn't mean that it's not there. It will reform but without the chakra stored.
Seal is not one time...I did mention that Sakura has definitely taken the time to think out how much chakra she has right now contained in the seal. She's measured it out and it took three years to get that precise amount. So, maybe her attack(s) will be using all that chakra at once. There should be no underestimation about how deadly her power can be.
Not to mention that afterwards, it won't even have to be three years the next time she wants to do that technique. It all depends on how much chakra she will feed into the diamond for an amount of time.
This is how I see it.
1. 3 years to form the seal
2. When it depletes, it may take 2 or 3 times longer than it normally does to replenish her chakra including the storage space but this is entirely dependent on just how much chakra she has in her storage. All I'm pretty sure of is that her stamina is a lot higher and she can push out a lot more powerful jutsu. I'd say it's easily at a 5 on the databook chart.
I saw your comment 
I dunno why he thinks Sakura's seal is temporary when Tsunade and Mito's seal is permanent. 
Like you said, why would she store chakra for 3 years for a one time jutsu?
I hope Team 7's gonna steal the show, I think so too. The rookies can only take the mini-Juubis, but Team 7 is on their way to the main body. 
LOL He's such a dumbass. I was shaking my head at how often she popped up in his review. She's the hot topic apparently. LMAO It's really funny when you think about it. 
Haha, after viewing that so called review, I absolutely HAD to comment. XD
I don't know why he thinks so either, but clearly, he doesn't know what he's talking about. He definitely hates her IMO, because he can't even appreciate what she's doing, and what's more is that this is the guy who said she wasn't anything heroic. LOL Just proves this idiot will never be satisfied.
I think they already did at the end of the chapter. At the end of the day, they're the only one currently capable of turning the tide of battle. It was nice seeing Rookie 9, but right now, all I truly want is Team 7 action moments. They're about to own the field with their teamwork!