I am one of the biggest Undertaker fans there is and I honestly would accept John Cena or a "rising star" ending The Streak if Undertaker has his final match is at WrestleMania (which it likely will) as long as that person is properly built from the momentum for 5-10 years after the event. Ending The Streak can't be just another accomplishment or feather in the cap for someone. They shouldn't do it just for the sake of ending it. That person's career should be MADE and they should be showcased as one of the very top stars in the industry after that. In Cena's case it would be further solidification of his legacy. If Cena isn't the one then WWE should find the superstar who has the right build, character, and the talent to sustain that build. I will be OK with that person ending The Streak if those stars align. If WWE can't do that then Undertaker should just ride off into the sunset with a perfect record at WrestleMania. He's earned it.
Cena doesn't "need" anything, especially not a huge WM win. He already has plenty (just see the list of people you named). That being said, if anyone on the current roster breaks the streak, it'd be him. And that being said, nobody is breaking the streak unless Taker wants it to be broken.
Not really, Taker wants Angle to end it at WM 22, but Vince rejected the idea and completely scrapped the plan to do Taker/Angle at WM 22.
And we all knew both Kane & Orton refused to end The Streak respectively at WM 20 & 21.