Ok, gotta preface this with the caveat that I am not a programmer. To some extent, I was back in the early 80's, but that's ancient history. The longest prog I ever wrote would not fill the comment section of a modern source.

That being said, the blockchain's data is a data set. How it's stored is important, but not as important as the data themselves. It is my layman's understanding that it should be possible to import all the extant data into an entirely new blockchain structure, if that was the intent. As an analogy, you can take an Excel spreadsheet and import it into a Lotus or OpenOffice spreadsheet, and all that changes is the formatting, even though the underlying code is incompatible.

But frankly, the blockchain is probably the most robust part of bitcoin, or any alt based off of it. In all of the attacks, glitches, assaults, and general fuckups that have occurred in the five years of Bitcoin, the blockchain has emerged unscathed. It's the programs that interact with it that have had problems. Even then, from what I've seen, most have been minor. Even this thing that Gox is using as their latest excuse appears to be something exploitable, if you have the resources, but not extreme. Frankly, Gox has been spreading confusion and delay as their standard operating procedure for the two years I've been involved in Bitcoin, so I don't even know how much credence to put in this. Bitstamp and BTC-e both thought it worthy of investigation, but were only paused for a short while. Gox has been having "technical difficulties" with withdrawals for as long as I've been a member here (a little less than a year), and I seem to recall them doing this kind of shit back before that too.