Amit Daryanani, an RBC Capital analyst, has suggested that if Apple did launch the iPad mini on the 12th of September, as speculated, then the company might sell as many as 40 million iPad minis in the first 12 months post-launch. That'd account for $10 billion in extra revenue which would equate to $1.15/share profit.
Daryanani hasn't really gone into much depth on how or why it'd be so successful - it also seems pretty strange given the lack of any proper specifications for the device - all we know is that it'll have a 7.85" screen. However it isn't too far fetched - when you look at Apple's share of the 10" tablet space, it's massive (they account for ~75-80% of it), so if they could do equally well in the 7" tablet space, it'd be a huge amount of shipments.
According to Forbes.com, another part of the report suggests that we'll certainly see more than just an iPhone launch next month, thanks to checks on the supply chain. He hasn't committed to the idea that Apple will launch an iPad mini at this time, as he also believes that a refresh of the iPad configuration is also on the cards. One thing that's important to note is Apple's secrecy - it hasn't even confirmed if it'll hold an event on the 12th of September, let alone reveal what it would announce.