IMHO: more decentralization is not possible with bigger blocksizes except you would accept that not every node keeps everything.
I believe there are solutions to increase decentralization and security with larger blocks, and before we discuss those options in detail we should first address how much decentralization is needed for nodes.
The scale goes from every user having a full unpruned node on all the time to no decentralization at all and a single database. We currently have ~6,400 live nodes on average for 3-5 million BTC users. Thus 1 node per 468 to 781 users.
what ratio and other considerations(I.E.. ASN distribution) should we aim for?
Personally, the concern for full node centralization is valid but not nearly as much as the security vulnerabilities we have from mining centralization where we essentially have a 4 of 7 multisig between the largest pools.
We need to tackle both issues however.
true, what is your opinion about letting the node owner decide which percentage he wants to share?
a good distribution about all asn's would be obviously a better alternative - with a decentralized opensource system like bitcoin its just not possible to force anything about the user.
e.g. if my server could not save the share bitcoin-core wants to save/distribute there are only two possibilities for me: stop my node or change the code to the size which works for me