Did you think about that what will happen in e.g. 2050 with this 'bitcoin chain'? Will it increase from 8GB to e.g. 8TB? 
If bitcoin ever goes mainstream I think 8 TB is too low to be considered a reasonable estimate for the year 2050...
Actually I think it's too high given the current protocol.
Assuming the protocol doesn't change, there is currently a 1 megabyte maximum size for a block. A block is added to the blockchain approximately every 10 minutes.
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Will it always be 1 MB / block - can this be changed? Will this suffice to process all transactions in future?