I think the likelihood that the original iPhone will continue to be supported is extremely slim. It is an old device; it was introduced well over 3 years ago now, and is just extremely slow by todays standards. That said, the 3G is slow today as well, but continued development is necessary as many are still in a contract for the 3G. So no, I don't think we'll see 4.0 for 1st gen. devices. 5.0 will probably drop support for the 3G too.