of course, this requires the other end to support it, which it probably doesn't.
I've also considered selling "multipath vpn" service... the idea being that people with two DSL providers (and one dsl and one cable) provider would setup their gateway (or use a linux box that I sell them and manage) to send all packets out VPNs on both connections, to my own vpn endpoint in a datacenter. The idea being that then my server on the other end of that connection would take the first packet and send it on to it's destination. Assuming that my datacenter has a good connection, you would suffer less packet loss, and less latency.
My solution here would solve the problem if the problem is latency/loss on your last mile connection. It would not help at all if the problem was further along the connection, while multipath-tcp would