There are too many bitcoin transactions, so the blocks are too big. The miners have to be run with different settings to account for that.
I don't know what bitcoin proponents think will happen in the bitcoin future when everyone will be payibg with it; the size of the block will quickly get to megabytes.
Meanwhile, average and available bandwidth and disk space goes up.
By the time the block chain breaks into the terabytes range, storage and network technology will have advanced to the point where it's not a problem anymore.
Someone on Reddit recently dug up this email from the early days of bitcoin development, from Satoshi Nakamoto (the founder of bitcoin).
He anticipated this problem and foresaw that eventually only specialized hardware would run full nodes, and everyone else would run on a highly simplified system requiring a lot less bandwidth/storage.
"Bank" carries a lot of unfortunate connotations with it that won't necessarily apply to the supernodes. It would be better to use a different term for those.
What's likely to closely resemble banks in the future are bitcoin clearing houses, where transactions just move around internally. These will be supernodes themselves, but not all supernodes need to be this kind of clearing house.
Yea. Everyone screaming Moore's law (a historical observation that isn't guaranteed to continue) must be also saying that the Bitcoin economy won't double from its current size every couple years.
Currently yes ( with the official client). But this is not a requirement of the system. Theoretically you can announce transactions without looking at the block chain, but then you do not know how much BTCs are in your account. There is another optimization, the block chain consists of an Merkle tree, such that you can verify the block chain without storing all the previous blocks. In this case you still need to download all blocks, but you only need to store ~ 80 Bytes per block. [1]
There is a hard limit on the size of the block. We are already 25% of the way there. This is going to become a problem in another couple of years, because the protocol cannot handle the rate of transactions.
