Well considering there is no justice league and superman, and all other heroes do not exist, i think what you said doesn't apply(in the nolanverse).^
This is not the comics, it is how nolan has chosen to portray the character, so far it would not fit in at all, he does not need more help than ever, he's stronger now than he ever has been, he has just successfully become the loner we all love from the comics(and as far as we can tell, defeated joker, although i hope two face and joker are brought back), robin is not essential to the transformation of batman(to film), although he may have been essential to the character.
Although I do see some of your positions on, batman cannot be in two places at once, he could feel strong regret, if there would have been two of him than maybe rachel would be alive.
If we ever do see robin, he will be darker than ever, there will probably no red or green, no crazy yellow, only black. Robin is a misshapen puzzle piece, but maybe nolan could chop down the edges, and retain the core of the character, he is a person for batman to talk to, they can relate in the since that they both felt great depression and loss. Now bruce has taken him under his wing much as Ra's did, but he wouldn't be crazy of course.
Although I am unsure if the character would be laughable or a complete Bada**, I wonder if nolan has given any second thought to the character.