I think it greatly depends on what you mean. MultiTouch Screen will be heavily featured on everything in the future as a controller, but the iPad as a musical tool it's really only every going to be a “Play Thing” to mess around on or a scratch pad for an idea or two.

It's operating system and it's price tag will ultimately be the reason why it will die a death very soon. Why buy an iPad with a limited closed OS when you can buy a full blown Windows 7 Tablet for less and that can do anything you want.

My 2 cents.
James.