Well hopefully we can expect the new iPhone, but nothing else will be announced (as available immediately anyway), it would just be lost in the iPhone v4 publicity drive.
Announcements of future releases of existing products doesn't happen, kills existing sales. So no new MP or MBA, well not for 4 or 6 weeks after the iPhone release. AppleTV may get an announcement, but no immediate release. If it does change, don't think it's going to be anything like the speculation already seen here, that's one tiny device, but it's just too small for a mass market product under the telly, and the only improvement is the selling price.
Will it stop people using their Xboxes and PS3's ? Sorry, no.
Include DVD-R ? No, then everyone will shout they wanted BluRay.
Will it be pure streaming, well I'd hate to see it, but I'm not sure how much longer DVD or even BluRay will be around. I love my DVDs, but Film and TV Shows especially, are disposable. You watch one episode of CSI or whatever, do you then pay $50 for the full revent series on 6 or DVDs ? How many will you watch again ? Films might be diifferent. Could be a success if they sort the pricing out. Only a fool pays $10 to rent a movie through iTunes when you can buy the DVD for $5.