As for the case of Mark Karpeles, I think it was more of poor company management skills. He fucked up yet he still kept dancing like nothing was wrong. I surely think that other exchanges have learned from this, But I cannot guarantee, that this will not happen again. Since centralized institutions are the weakest link of bitcoin. If we'd move on to decentralized exchanges then this would not happen. However decentralized exchanges are still in quite early stages of development.

I think the regulated exchanges will not be MT Gox 2. Most of the unregulated exchanges will be.

I can't see how we could ever have something on the same scale as that.  Gox happened at a time where people literally kept every last satoshi on the exchange and treated it like a bank account.  I'd like to think no one is crazy enough to be doing that anymore, although there's probably a few people that do. 

Also, because people were so trusting, some of them were still depositing funds even after the warning flags started waving.  I recall lambasting people to withdraw their funds if they got the chance, but instead, some plowed more money in because the price went down and they thought they'd get a bargain.  The general atmosphere around here would be so different if something similar were to happen now.  Far more people would take notice if they were warned that an exchange was in trouble.

i think cryptsy will be a second mt gox 2 incident someday in future .because, payments of cryptsy is not regular nowadays.

I don't see how there can be something of the scale of Gox again. It was pretty much the entire bitcoin gateway for a long time. That can't happen again. Can notable exchanges fail and take coins and funds up in smoke? You bet. There are still plenty out there which are operating in something of a grey area with some pretty shocking procedures. It's up to the people using them to vote for trustworthiness by leaving them behind.

Cryptsy is Mt Gox version 2.

But Cryptsy is using the same excuses like Mt.Gox right - getting hacked, delayed & cancelled withdrawals and so on.

DDoS attacks do not necessarily have an impact over security of the exchange, all it does is force it to stop their services.