From what i understand when bitcoin reaches 7000tps each block will be around 1GB in size.
how will then new nodes be boot strapped from scratch?
by the time the node finished verifying every transaction since bitcoin's inception the block chain would have already expanded by many new blocks
The max block size is currently a thousandth of that and only rarely do blocks even approach that size.
Even so, there are already numerous development efforts aimed at reducing the blocksize and speeding up bootstrapping of new clients. Looking up "pruning" would be a good start if you are interested in more details.