I spent some time on X.25-ish
Multi Link Protocol (MLP) in the late 80s - would love to see TCP
running over three gig-E interfaces, but not if it's sensitive to
out-of-order delivery.
What is sensitive to out of order delivery? The GE interfaces or TCP?
As soon as you start using multiple links in parallel, you're going to
see out of order packets, that's pretty much guaranteed. (Consider the
case where an application sends 1800 bytes worth of data, so a 1500
byte packet is transmitted over link A and a 300 byte packet over link
B. The second packet will get to the other side first because it's
shorter.)
If TCP has problems with out of order packets, then it hasn't been
implemented terribly well.
I have no doubt that as soon as we have mechanisms for multiaddress
multihoming, we'll see people trying to load share across the different
addresses. This could be very useful.