Log operators seem to have largely settled on the idea of sharding logs annually by expiry date (?). This will allow a log to be "closed" to new entries and the maintenance wound down in an orderly fashion so that logs don't grow endlessly.
There's a fun interaction between this and changing expiration rules. Ballot 193 changed the maximum expiration to 825 days from 1 March 2018 (ie a few weeks ago). So in February 2018 it was possible to renew a cert with, say, DigiCert and have the new cert expire in May 2021, 39 months later (the CAs didn't tend to sell 39 months directly to end users, they used the extra 3 months to "carry over" time when you renewed a certificate for three years, likewise they don't now sell 825 days, they sell 2 years and just "carry over" the extra days). Today the latest a new cert (including a renewal) could expire is June 2020. So the 2021 logs are no longer really filling up for another six months.
We've got a couple improvements in mind, e.g., rolling up roots by ownership, drilling into individual certificates, etc. but curious to hear what the community would like to see.
There's a fun interaction between this and changing expiration rules. Ballot 193 changed the maximum expiration to 825 days from 1 March 2018 (ie a few weeks ago). So in February 2018 it was possible to renew a cert with, say, DigiCert and have the new cert expire in May 2021, 39 months later (the CAs didn't tend to sell 39 months directly to end users, they used the extra 3 months to "carry over" time when you renewed a certificate for three years, likewise they don't now sell 825 days, they sell 2 years and just "carry over" the extra days). Today the latest a new cert (including a renewal) could expire is June 2020. So the 2021 logs are no longer really filling up for another six months.