here's my opinion on the matter.
iPad? it's a must. iPhone? not now, too early.
iPad
I think taking out the Home Button is a must, because it's just taking space for nothing really. Once we get used to the gestures for Home, Switch Apps and Multitasking Bar (and you all know we WILL ALL eventually get used to those); the home button will not be needed anymore. PLUS, when u get "submerged" into the iPad (specially in landscape mode), sometimes it's kinda awkward looking for the home button to click it.
now, for the people talking about the hard-reset and stuff like that, you still have physical buttons: the lock button and the volume buttons. they can do the volume buttons of the iPad 2, just like the ones of the iPhone 4: separated. that way, to do a hard reset you'll have to press the lock button with one of the volume buttons instead of the Home button.
iPhone
I think it's too early only because, like most people said, the screen of the iPhone is just too small for 4/5 finger swipes and gestures. so it's a no-no. BUT, as far as everything else goes; the hard-reset, the voice command, the double click to open cam (for us who still have that option), it can all be assigned to a single or even both volume buttons. Apple can always find a way.
What do u all think?
[EDIT] on the iPad it would actually look nice, because the space between the screen and the edges is almost the same from all sides. on the iPhone it would just look wrong if they cut it out from below and it would only have that extra cm on top for the earpiece and cam.