Am I the only person who doesn't think of the current iPad as "iPad 4"?
Yes, it's the 4th generation iPad. It had a minor revision recently to bump the processor, tweak LTE support and add the (frankly mandatory) Lightening connector.
Will there be another iPad revision in ~6 months? Possibly, yes. This is a very new and fast growing market with intense competition, tablets are going to need to stay current in order to compete.
Maybe we'll even get a new enclosure in ~6 months time, but I'm guessing that's more likely ~12 months away unless they find a way of slimming down the huge battery/tweaking the Retina display.
The iPhone, I think, will retain its current naming strategy. The iPad is being treated much more like a computer by Apple. It's "The iPad", like "The iMac". Major redesigns will be trumpeted every now and then, but we'll see minor revisions along the way to keep it current.
That's how I see it, anyway 🙂