Well, once I go 1080p, the MKV version will be 1080p BD50 sized, then maybe also a 1080p BD25 and then a 720p AVCHD - I think 7GB is just not enough for quality 1080p, so the AVCHD version will still be 720p and there will probably be a DVD5, as usual.
Very glad I have extra HDD space for these awesome projects