Wouldn´t it be possible to update the size of blocks to enable more transactions when this become a limiting factor for transactions? I.e when the average number of transactions is 7 per second, the size increase to 1,5 MB. When the number reaces 10, increase to 2mb end so on and so forth... Or is changing the blocksize a difficult technical issue?
It is just changing a parameter in the source code.
The difficulty is getting everyone to agree to it. If they boost it to 2MB, then older clients won't accept the new blocks.
You have to convince everyone to upgrade.
There is a 32MB limit to the size of messages in the protocol. At the moment, blocks have to fit in a single protocol message. Going past 32MB blocks would mean a protocol change of some kind. Maybe blocks could be split over multiple messages.
Increasing that could make networking a little more difficult. It isn't that big an issue though.
If you increase to 2MB, then the size of the blockchain potentially doubles. That means more hard drive usage.The tradeoff is that a small block size means less load on the nodes. This means more nodes and so the system retains its decentralize nature.
A larger block size means more transactions per second, so the network can expand more.
But we're are talking about distant future, the network, cpus, drives, all of these will be faster and bigger with time. So why didn't Satoshi decide to limit the block size to 32 MB at the beginning?