If the bitcoin community decided to send transactions at the maximum rate and all miners were to produce 1MB blocks, at 1 block every 10 minutes 50.6GB (51840MB) will be added to the blockchain per year. It will take 20.2 years to add 1 terabyte to the blockchain.

A 3TB drive commercially available today will be able to store the blockchain of a bitcoin on steroid for more than 60 years.

"640K 1T ought to be enough for anyone".