Besides the dynamic bandwidth allocation, you pretty much described how USB 4 and all versions of Thunderbolt works.
Personally I'd hate to see my display bandwidth drop when I copy files to a flash drive so I'm glad no monitors support that part of your suggestion. Input lag = horrible UX.
> I'd hate to see my display bandwidth drop when I copy files to a flash drive
Well… if you connect the flash drive to the monitor and not the computer that should be expected. OTOH, I’d love to have faster data rates when my monitor image doesn’t change much (such as when I’m writing code or letting the computer move lots of data between external drives.
You're limited by the cost per PHY. Instead of adding a 40G port to your monitor, it would cost almost the same to add it to your PC and avoid the bandwidth contention. Most monitors only support 10G which is dirt cheap.
Also USB4/thunderbolt already lets you use the same PHY for either a monitor or a flash drive
Personally I'd hate to see my display bandwidth drop when I copy files to a flash drive so I'm glad no monitors support that part of your suggestion. Input lag = horrible UX.