Totally. I watched it with two friends.
We all yelled a lot and held each other in fear.
This is why you're Grand Poobah. You are absolutely correct.
See, Hiro's ****ed.
Sylar was never the bomb. But Hiro doesn't know this. Even if Hiro succeeds in killing Sylar, he won't stop the bomb. That said, it's possible the future will still be better post-bomb because Sylar won't be the president. But, as Sylar said, Nathan had already turned against his kind before Sylar killed him... so maybe not.
This is however the big thing - stopping Sylar and stopping the bomb are two separate, but linked goals. And this is ultimately why Hiro will always fail - changing the past only works if you have omniscience of past events. Future Hiro thought he did, but because he's wrong, he can't guarantee the future he wants.
Also - let's get into Hiro's powers.
If we recall, Hiro can change the future. There is no way Ando will be called on November 8th and say, "I have not seen Hiro Nakamura in 5 weeks." We know this because Ando and Hiro have been road tripping across the US and because Ando is supposed to die in the explosion.
Hiro can change the future.
But he can't change the past.
Whenever Hiro travels back in time to change the past he fails, as he did with the waitress Charlie. And Future Hiro failed to change the past.
See, he says he couldn't kill Sylar and thus, stop the bomb, because he had regeneration. But the Future Hiro HAD to be wrong. Because Sylar couldn't have had regeneration because Claire was still alive. He didn't know. He didn't know that Peter was the bomb. Future Hiro got it wrong. Future Hiro telling Peter to save the cheerleader is the event that causes this future. It's pre-destination. Hiro can't change the past. He never has been able to.
See - when Future Hiro went, "If I go back here and tell Peter to save Claire, it's all ok" he did that because he thought Sylar was the bomb. He was wrong in his assumptions, and when he told Peter to save Claire, he didn't de-rail the future at all. It continued on its merry way.
But Hiro can change the future. When Hiro jumps to the future, he sees the future that exists if he never jumps. We've seen this is how his power works already. So when he jumps back, he can alter it, simply by having seen the future (much like Isaac). But he can't change the past since that would prevent him from existing and thus, changing the past.
Does this make sense?
As simple as I can - Hiro can't change the past, but can change the future, releative to his 'present'. 2007 Hiro can change any events 2008 onwards, but not 2006 and before. 2012 Hiro can change events 2013 onwards but not 2011 and before. Future Hiro was wrong, and Peter will still go boom and Sylar will become president. Present Hiro can stop Sylar by killing him, but he can't stop the bomb since he doesn't know it's Peter.
But there are two flaws with this -
1) How come Peter has a scar? If Claire did indeed die in the first place, then Peter wouldn't have regeneration and thus - he'd have a scar. But Claire didn't die. She's alive in the future. Which means Peter saved her. Which means, he has regeneration, which means he shouldn't have a scar.
2) How did Sylar heal himself and survive his confrontation with Hiro? The only possible explanation other than Hiro simply didn't deal a killing blow is this - Linderman healed him.
And then we have the "Linderman Act"... does Linderman know Sylar exists and does he actually want him to take over from Nathan? Or has Sylar eaten Linderman's brains by that point and healed himself?
And how did Parkman not know Nathan was actually Sylar? He can read Sylar's mind, he should know the president is being impersonated. This means one of three things - Parkman can't read Sylar's mind, Parkman never tried to read Sylar's mind because he thought he was the president, or Parkman did read Sylar's mind and didn't care. Parkman does look disconcerted by Nathan's powers when he attacks Peter... but doesn't seem to have any on-screen reaction when Sylar reveals he's Sylar (unless the illusion is only dispelled for Peter).
Another thing of note - Bennet hid, when Hiro gave them over to him, DL, and Candice. Sylar ate both their brains. Now, I assumed that he got to DL because Parkman knew about DL from reading Bennet's mind, told the president, who then ate DL. But, that can't be true for Candice, since Candice's power is what lets Sylar become the president...
And just what can Molly, a little girl, do that's useful in a prison break? Did future Sylar eat her brain too? (She was on the same list as DL and Candice, both of whom, Sylar devoured.)
This is really exciting.