Well, as long as we are guessing here, lets have some fun. I think apple will eventually merge the two O.S they are currently developing. The OSX will be reduced to a cloud based, iphone type OS that is cleaner, faster and and more reliable than what they have now. For 10.7 or OSX Serval, apple will start to introduce this merger. Why have two OS's when one can work for both? The iphone OS natively runs on multi-touch technology, OSX does not. The ipad's success will probably set the mood for future mac touch screen OS development. If it fails, they will probably re-examine where they go, if it takes off, which it might ( i plan on buying the entry level ipad) I think it will lead the way for a merger of the two OS's. The fact is, multi-touch is here to stay and apple will lead the way, thankfully, because Microsoft just doesn't get it.
What's Next for Mac OS X?