According to Amazon Germany the Iron Man 3 DVD release date has been scheduled for October 2013. The German site has historically been early to post these types of details, however eventually the confirmed date for the US and other territories is roughly around the date they mention, so we can probably expect the DVD/Blu-ray release around September/October. This would mean a 4 or 5 month window between the theatrical and home media release, which is consistent with previous Marvel DVD/Blu-ray releases.
The movie has reached $740 million worldwide so far and is well on course to cross the $1 billion mark. It won’t reach the $1.5 billion made by The Avengers last year, but it can still be considered a great success regardless. Iron Man 4 will obviously be a major consideration for Marvel and Disney going forward, it just depends on whether Robert Downey Jr. will be involved. Marvel Studios President Kevin Feige has said the franchise could continue on without the actor in the same way Bond and Batman have been recast in those franchises.
As we can expect the Iron Man 3 DVD/Blu-ray in September/October it could contain a preview of Thor: The Dark World which opens in November. I suppose there could be something to tease Captain America: The Winter Soldier and Guardians of the Galaxy too. Maybe even The Avengers sequel.