Just found a simple equation to balance supply and demand that could be easily introduced in btc source code:
next block size limit = previous block size limit + (total fee in the last period / avg fee in the previous period - space used in the last period) / block occupancy rate for the last period
Now I challenge you to find an equation based on "not centralizing bitcoin too much".
No, there is no such equation, because a block size increase, increasing transaction thoughput, also increases the hardware requirements, and bandwidth requirements to run a full node, and it scales the network in.