I can't help wondering if these comments have been a bit overstated. I have no doubt that Batman movies will continue to be made after Nolan, Bale etc finish with them. As we've seen with Spider-man, Hulk, Punisher etc, the gap between one series ending and a new starting gets shorter and shorter. Funny how when Batman Begins was announced way back when, many thought it was far too soon after the end of the Shumacher/ Burton movies to start over again!
However, I'd be surprised if Nolan remains on in a production capacity. Surely if he wants a definite end to his series with TDKR he wouldn't want to be involved in a new version of Batman? He's said what he wants to say - why would he hang around if this is someone else's take?
I think that the idea of TDKR proving a first in how it 'ends' its tale is also a bit overstated. As has been said already, X-Men 3 did the same, killing off Xavier, Cyclops and Jean - mainly because of Tom Rothman's dumb idea that trilogies were essential and a series couldn't go beyond a third movie.
If Nolan goes down this line and ends with Batman dying, retiring or being crippled, then fair enough, whoever comes next will have to reboot it. But I'm with those who have said that the series should continue like Bond (pre-Casino Royale). No explicit references to what has gone before but nothing to expressly rule it out either. I would have preferred this to what seems likely to be in the vein of the Spider-man reboot.