Pretty simple. He caved into editor pressure since a while ago (before RtN). But decided to do RtN to please us while he pleases the NH fandom through the manga. At least that's my take on it.
A little bit on the pessimistic side, but hey, you're entitled to your opinion.
I'd rather have faith that Kishi is not such a petty individual to actually give some sort of pathetic consolation prize because a pairing won't happen. Despite his flaws he's written a very powerful story.
You say that his procrastination will get back to him, but the thing is that he's done that before and yet he still reigns as a top mangaka. That means that he's still doing something right in the eyes of his audience. Otherwise he would drop from the polls just like it happened with Bleach.
Also, don't you think you're taking the editor influence a little out of proportion, at least when it comes to pairing drama? This is an action series, the romance is a plus but not a determinant factor. Do you actually think the editors are worried that the target audience would drop the series because a certain pairing doesn't happen? Not to mention that a final pairing would only happen near the end, so I don't think anyone would want to quit the series when they have come this far.
I sometimes think that all of these worries of Sakura being forgotten and Hinata taking the spotlight are just a little too much. When Kishi wants Sakura back, he'll simply bring her back and that will be that. He's done that with a lot of characters (whether they are main, secondary, or minor) so I don't know why Sakura would be different.
As I've said before, if Sakura just keeps healing in the background then I'll completely understand why people would complain about Kishi's lack of attention. After all, he did make Sakura say she would fight together with Naruto. But the thing is that until the battle is over this disappointment is based of speculation.
If Sakura does end up fighting together with Naruto, does something cool with her strength, gets a kyuubi cloak, or else whatever to impress us then people will just focus on her present actions rather than keep wallowing at her previous absence. I believe Kishi knows this, therefore, just reserves her from when the time is right, like with many other characters before. Kishi also knows that people aren't gonna drop Naruto just because Sakura isn't appearing. 2 or 3 people might, but do you really think Kishi will pander to 3 people? Not really.
That's why I believe he doesn't mind withholding Sakura in the meantime.