"If each node has to verify all transactions that is not sustainable in the long term."
It is sustainable, but only for certain amount of transactions. Even if the block size limit stays at 1MB, I'm pretty sure some group of people/organizations will keep using bitcoin for something. Those who are not happy with it will move elsewhere, but there is so much infrastructure/tools/etc for bitcoin already, that many have will hard time switching to something new.
It is sustainable, but only for certain amount of transactions. Even if the block size limit stays at 1MB, I'm pretty sure some group of people/organizations will keep using bitcoin for something. Those who are not happy with it will move elsewhere, but there is so much infrastructure/tools/etc for bitcoin already, that many have will hard time switching to something new.