Increasing block size wont scale anything. You get scaling when two processes can work in the same time without waiting on the other.

With blockchain it would mean two or more blocks could be mined in the same time without waiting or depending on each other.

Increasing block size or decreasing block time increases throughtput but doesn't increase scaling.

 The only one valid next block concept prevent true scaling , as all miners/stakers need to synch on the next block, and cant "advance" The blockchain each on their side.

To have true scaling it would require to distribute tx across miners for that they can each mine a different block in the same time. But with current blockchain principle that cannot happen as only one of the two block would get accepted.

Having a double chain system would allow cheap scaling.

To me the only thing that truly prevent mass scaling is the competition for block reward. Without this, many secure scaled system can be thought of.

The logic of coin emission control via block reward make it difficult to scale easily, as the total coin supply need to be controlled on the whole network, if a consistent emission curve is to be maintained.

I guess when cap is reached and emission curve flaten, scaling become easier.