Would it not be possible to buy a harddrive with the blockchain already on it?
Downloading 700GB P2P, I guess that would take weeks or even months.
Every package sent around the globe usually is faster.
In 4 years, a 700 GB USB stick will be a normal thing.
you must still be on dial up or something
700GB can be downloaded in less than a day on 4G Connection (80mb)
it would only take 9 hours to download 700GB today on a 200mb connection (fibre)
(which are available in certain developing countries already for $50/month)
you might want to look at:
http://www.download-time.com/700GB in 4 years will be nothing in most countries