You can easily say the same thing for arm taking over the x86 market,the way things are going now I can easily see arm cpus taking over the pc market.
take a look at the google chrome book laptop,its using an arm a15 dual core and I can see that taking off big time in the next few years
I'm not sur that ARM will ever take over but it would certainly be interesting if they did.
At the moment Intel controls the desktop space very tightly, they have incredible manufacturing and R&D experience and a very tight grip on X86 licences.
ARM are pretty much the opposite. They aren't a manufacturing powerhouse and are free with their licencing.
They are very different philosophies and it would be interesting to see what would happen if ARM 'took over'.