I have no idea, but that's an interesting thought. However, our borderguard is at 8km and nobody has made a portal that far out in the overworld. In the nether though, that would be like 4km (or maybe 2km? I forget the number that is used to find nether coords vs overworld) in the nether and I don't think anybody has gone that far in the nether yet.
I don't believe in borderguard, so as long as I am the one doing the plugins, borderguard won't happen.
Wait until Fiah or someone decides to go 20km, lol.