I want to open a full node now (not for mining but for developing) and I can't because it's too big!
You don't have 100 GB of storage? Otherwise, I don't see why you can't. Optionally you could run a pruned node.
700gb is x700000 then the current block size, even if the whole world are going to use bitcoins at a daily basis we won't need such a block size.
No, you don't understand what is being talked about here. They are not talking about 700 GB blocks, but the blockchain size growing towards 700 GB (currently ~100GB).
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Obvious spam post. You have clearly read nothing and just wrote up some nonsense that you think is relevant when in fact it is not.