Well, if you look at the number of abandoned alt coins and torrents out there, it seems far from permanent. Coinopsy has a list of abandoned coins if you're cu

Well, if you look at the number of abandoned alt coins and torrents out there, it seems far from permanent. Coinopsy has a list of abandoned coins if you're curious. And even if you had history in a blockchain, it's possible for someone to prevent you from seeing the blocks that come in the future (breaking/filtering your internet connection), which is also in a sense changing history (by means of denying the future).