There already are lossless video codecs. The problem is that you can't currently compress a lossless movie down to a size that will fit on a disc (even Blu-ray sized, maybe possible once more than two-layer discs are available, though it won't be HD).

So lossless isn't really an option, what is is better lossy codecs. MPEG2 was never really that great, whereas MPEG4 is quite decent already. Most Blu-ray and HD-DVD movies will be encoded using one of two MPEG4 based codecs and therefore will be much better quality already, maybe enough that you wont notice any more artefacting, plus they will have the bonus of even greater horizontal resolution.