You can't include external data without oracle or someone who you must trust.
Maybe we can use Mining difficulty as a predicting tool for the price?
When bitcoin prices rise, mining profitability will rise, resulting in more people mining, and therefore increasing difficulty. we need to factor in mining hardware improvement though (Updated Moore's Law?)
is the validating process really significantly increase with that blocksize? i think if there will be any blocksize increase, it should be increased to the point where mini-computer like Raspberry Pi still can handle it.
and BTW, isn't that utreexo is just like a pruned node but with "compressed" UTXO?
I think, for now, there's no need for blocksize increase yet. the recent increase in bitcoin transaction fee are most likely because the significant price increase, and it maybe won't last forever, once the price fall significantly, the transaction fee will go down too(2017, mid-2019). there needs some long-term transaction fee increase to make it worth it to increase the blocksize. Maybe when we start using bitcoin as a method of payment, not as speculative asset.