It's possible, FTTH should be able to scale up to 90-100mbps with a few accounts over a single line. One of the early methods to uncapping Unifi was to bond multiple PPP interfaces using the same account.. which is how I used to get 100mbps That's patched now but you should be able to use a single Linux router box + multiple accounts + load balancing to achieve what you want. You'll only see the effects on P2P applications such as BT though.