I can't agree with you. We've known for a long while more tablets were on the way. Nothing is lighting the lamp in terms of being able to truly compete with the iPad yet. That's when the war will really start.
The war's already on. Alternative tablets are out there already, more are on the way.
I see this as being no different than the smartphone wars. Apple makes the iPhone. Yes, it's probably the best selling *individual* phone....but if you took all Android phones, for instance, they'd add up to very strong opposition, even if none of them were individually selling the iPhone. And I don't think it's realistic to expect otherwise. I mean......how many different Android phones are there? How many different Blackberries are there? I'm sure if Apple manufactured multiple models of smartphone, the iPhone wouldn't be nearly as individually dominant as it is now.
Same for tablets. In terms of consumer devices (given that Apple didn't invent the tablet computer), the iPad hit first and has become very popular, in the absence of competition initially. However, there have been increasing numbers of other tablets coming out. There'll be a bunch of Android tablets. There's the RiM Playbook. And there are even Windows based tablets.
It's going to be death by a thousand cuts. The Apple product may or may not stay on top. Simply by virtue of how many have been sold, it could very well stay on top. It'll be a few more years to know for sure. But if there are a bunch of competitors, they'll make a difference in time.
And, as to sales numbers? I don't think anyone is expecting iPad like sales numbers initially. I've read the Xoom sold something like 75,000 copies in a month. For a $600-800 device, that's a fair chunk of revenue. Maybe only 6% of the sales of iPads in a similar time period....but if you start combining Xoom, Galaxy Tab, EEE tab, Playbook etc. they'll all add up.
Incidentally, I've tested out the Playbook in the last several days, and it's quite a nice device. Faster than the iPad, nicer interface, proper multitasking, better browser, Flash support etc. No, it doesn't have the app store..but if you have Flash support, that's less necessary. As an example, on the iPhone, I need to install the SpeedTest app, to run tests through SpeedTest.net, because Flash isn't supported. With the Playbook you just use your browser and go to
Speedtest.net - The Global Broadband Speed Test and it works flawlessly. And it's going to run both Playbook apps and Android apps. The power button is a pain as it's rather small, and it's currently lacking an e-mail client and calendar app, but those are coming in a few months. RiM has excellent longterm support for their products, with regular software updates.
Banshee