The other option would be to change the block time to 2 minutes.
I'm not sure why that wasn't discussed more.
Because that will cause more frequent orphan blocks. It has been said in this kind of threads before.
I'd like to see an estimated % of increased orphan blocks at 2 minutes. Then weigh that against the inconveniences that will arise from 20 Mb blocks. Pretty sure a "slightly" higher increase in orphans would be preferable. Still, I'm sure Gavin and co have their reasons.