we can expect all the above mentioned, but i doubt if we'll see all the deleted scenes. after all, just look at EpII's DVD in which some deleted scenes were held back. just get ready for the ultimate-super-duper-all-in-one boxset of the saga or something.
yes the OT boxset was cool indeed, eventhough Lucas held back on the deleted scenes.
i don't there's any official announcement about a Prequel boxset yet, but it was mentioned at ComingSoon.net that there might happen at the same time when the Episode III DVD comes out. I'm thinking that just lower price perhaps, because I'm not going to buy a Prequel boxset with the existing Episode I and Episode II DVD - I already have it.
Unless some new stuff are added into, I'll wait. Lucasfilm will need some time to prepare a good DVD boxset worth the fans money.
at some point in the future, even if we have the current OT DVD boxset, we're sure going to have to get another OT set, one that comes with the Prequelsl (as Lucas now sees Star Wars as one single movie). Even on the current OT boxset, there are bloopers included as an easter egg. do a google search and you can find how to access it.