For example with an arbitrarily large MAX_BLOCK_SIZE, a mining group hostile to the success of Bitcoin with 1.1% of the network could feasibly solve 1.45 blocks per day on average. If they did so with very large blocks, such that fully 1/3 of their blocks were orphaned and was sending 1GB blocks, this could grow the block chain by 1GB per day.
Absolutely, but scaling the block size according to the projected bandwidth growth rate (based upon the recent bandwidth growth rate) means that 1GB blocks are still many years away, mid-2020s. Storage shows phenomenal potential for further growth and durability.
http://physicsworld.com/cws/article/news/2013/jul/17/5d-superman-memory-crystal-heralds-unlimited-lifetime-data-storageIn ten years time the block reward will be 3.125 btc, and the fees market much healthier, such that a dynamic "soft" limit could be introduced, if that is considered needed. You mention doing the right thing for future generations of Bitcoin users. We all want to do the right thing for them, but we have to concede that they will have far more information to make design and scaling decisions. What is important now is to introduce *some* scalability, ideally so that the ecosystem can grow, as much as computing technology (in the hands of a hobbyist or semi-professional bitcoiner) will allow, in the meantime.