The cap is around 27Mbs. HD streams are ~7Mbs and SD is ~3Mbs. Most homes sync at a max of 60+Mbs. Thus there is enough room to add 2-3 more simultaneous HD streams and up the data rate to 12+Mbs. Advanced MPEG4 compression technology should be able to squeeze HD to 6Mbs soon, so the available BW is more then enough to compete.
