Regarding history attack, I will introduce in this topic another very interesting idea from NXT that is not yet implemented but could solve concerns with hidden history rebuilding, it's called Economic Clustering.

In Economic Clustering, basically, all transactions have to include a signed reference to an older block or transaction in the history, so if an attacker gets the keys of an account that used to have huge amounts of stake (those close to the genesis of the coin) and tries to reconstruct his/her own version of history in isolation it's impossible to rebuild it including the transactions of the rest of the economy and collect any of their fees, simply because the hashes of the new history will never match those included in the transactions previously broadcast.
If you already belong to the network and see the hidden branch being released your client can immediately spot the fake history as not including any transaction that you know about (from you or from a list of known companies/entities).

I see it as a social consensus: to fool the history you need to pro-actively involve a majority of the network signing the scam.