Note that many of the terms which are "generic" in north america such as Aspirin or Ozonol and not common elsewhere in the english langage because those products are either sold under a different name elsewhere, or another product is more popular. In Australia, they tend to use "paracematol" to refer to pain killers.
Heck, at one point "7-up" was generic term to denote colourless fizzy drink in north america, but that brand has fizzled out due to competition and the brand being shifted from one onwer to the next. (In australia they call those drinks "lemonade".)
I think it is too early to tell whether "iPad" will become generic. And it will be the younger generation which decides.
I think the last such precedent was set by Sony and its Walkman. I still think "walkman" when I think of my ipod or my iphone in music playing mode.