if memory serves I read somewhere that the cap on the block size was introduced due to DDoS attacks against the network using very large blocks, is it correct?
Due to the potential for such attacks.
I like to think that, like myself, sidechains at least occurred to Satoshi early on in his ruminations about scaling modes. Likely we'll never know though. For my part I imagined the name 'child chains', but whatever. Same diff. They are just a logical sub-set of the Bitcoin solution one way or another.
I actually had a similar thought experiment the other day.
Imagine that Satoshi had built sidechains out the box with Bitcoin.
Would we be worse off
or significantly ahead?
I think sidechains are the most natural extension possible to Bitcoin if they can execute what is in the white paper. Of course that remains to be seen but considering just about all of silicon valley invested in their 20 million seed round. My bet is they will.